CA2288340A1

CA2288340A1 - Integrated ain busy call return/ain call forward on busy feature

Info

Publication number: CA2288340A1
Application number: CA 2288340
Authority: CA
Inventors: Foad Mojgani; Julie Chen; Honsan Chung
Original assignee: Nortel Networks Corp
Current assignee: Nortel Networks Ltd
Priority date: 1998-12-21
Filing date: 1999-11-02
Publication date: 2000-06-21

Abstract

A method is disclosed of conveying information from a caller to an intended recipient along a telecommunications network where if the call cannot be placed initially because the recipient at a directory number (DN) is busy. The network prompts the caller to select between either leaving a message at a forwarded location associated with the recipient's DN, whether voice mail or otherwise or to be disconnected and subsequently reconnected with the intended recipient when the recipient's DN is no longer busy. If the caller chooses to leave a message, the network connects the caller's DN with the forwarding DN and a message is left. If the caller chooses to be connected with the recipient when the recipient's DN is no longer busy, the call is terminated, the recipient's DN is monitored so that when the recipient's DN is no longer busy, a call is set up by the network between the caller's DN and the recipient's DN, whereby the information can be conveyed.
Apparatus for implementing this method using the advanced information network (AIN) protocol is also described.

Description

Integrated AIN Busy Call Return/AIN Call Forward on Busy Feature FIELD OF THE INVENTION
This invention relates to telecommunications networks, and in particular to telecommunications systems offering automatic call back and call forward or voice mail functionality to telephone subscribers.
1o BACKGROUND OF THE INVENTION
The deregulation of the telecommunications industry in North America has created tremendous competition between telephone service providers. In their efforts to attract customers, more and more customized service features are being supported. The varying requirements of each of these service features may sometimes come into conflict.
One of the more prevalent service features is the Call Forward feature, whereby the subscriber may direct incoming calls to his or her directory number (DN) to be 2o forwarded to another DN, without causing the customer premises equipment (CPE) attached to the subscriber line with which the subscriber's DN is associated to ring. Thus, for instance, if the subscriber is away on vacation, the subscriber's incoming calls may be forwarded to an assistant who could take a message 2s to be subsequently returned by the subscriber.
Enhancements to this service feature include Call Forward On Busy and Call Forward On No Answer, in which, respectively, the Call Forward feature is only invoked if the subscr:iber's DN is busy or the call is not answered within a 3o predetermined number of rings. These enhanced features are typica:Lly invoked on an ongoing basis, as opposed to the basic Call Forward service which is typically invoked on a situational basis by the subscriber (ie. when the subscriber does not wish to be disturbed).
3s An application of the Call Forward family of service features is the Call Answer feature, described in the Nortel DMS supernode MDC Feature Library (1Q '96). When the Call Answer feature is subscribed, a voice mailbox with a virtual DN
is created and associated with the subscriber's DN and the Call Forward, Call Forward On Busy or Call Forward On No Answer s feature is provided, with the forwarding number being the DN
for the voice mailbox. Thus, when the terminating DN of a subscriber is busy, the caller is given the opportunity to leave a message at the subscriber's voice mailbox, which message the subscriber could later return if appropriate.
to The Call Forward feature and its enhancements (including Call Answer) deal with incoming telephone calls. In the context of telephony, a call is described in terms of its outgoing or originating component and its incoming or terminating component. Thus, the feature may be considered a i5 terminating feature. In any given telephone call, the switch which must implement the feature is the switch to which the terminating CPE is connected (the terminating switch).
A more recent service feature is the Automatic Call Back (ACB) feature, whereby, when the DN of an intended 2o recipient (the terminating DN) of an outgoing call is busy, the caller may invoke a feature code and dial the terminating DN.
When this is done, if the terminating DN is not busy, the call will be connected. If the terminating DN is busy, the call will not be connected. Rather, the caller will be subsequently 2s notified by a distinctive ringing tone at its CPE when the terminating DN is no longer busy. Upon answering the phone, the caller is automatically connected with the intended recipient at the terminating DN. This ACB feature is described in Nortel document AG0728FN.AH02 (Class - Automatic Call Back).
3o A potential variation to the ACB feature, known as the Enhanced Busy Call Return (EBCR) feature, removes the requirement that the caller dial a feature code and dial the terminating DN. Rather, if the caller subscribes to the EBCR
feature, the caller need only dial the terminating DN. If the 3s terminating DN is not busy, the call is connected. If the terminating DN is busy, the caller is notified of this fact and requested to choose whether the EBCR feature is to be invoked for this call. If the EBCR feature is not invoked, the call attempt is simply terminated when the originating CPE is placed on-hook. If the EBCR feature is invoked, the call attempt is s again terminated when the originating CPE is placed on-hook, but, as with the ACB feature, the caller will be notified by a distinctive ringing tone at its CPE when the terminating DN is no longer busy. Upon answering the phone, the caller is automatically connected with the intended recipient at the io terminating DN. This EBCR feature is described in Nortel document AJ4122FN.
As opposed to the Call Forward feature, the ACB (and the EBCR) feature is an originating feature, because the subscriber to the feature is the caller, rather than the 15 recipient of the intended call. Thus, in any given telephone call, the switch which must implement the feature is the switch to which the originating CPE is connected (the originating switch).
Both the Call Forward on Busy and the Busy Call 2o Return families of features may be implemented in respect of a given call, because the latter is an originating feature and the former is a terminating feature. However, to date, the features have not been offered in combination.
In typical switch-based implementations, the two 2s families of features would come into conflict. This is because the implementation of the Busy Call Return family of service features requires that the terminating switch must return a "Busy" indication to the originating switch. Where the Call Forward on Busy family of service features is invoked for the 3o terminating DN, however, such an indication cannot be returned, because the terminating switch, having been directed to forward the call, to the voice mailbox or otherwise, considers the call to have been connected. Thus, the potential for the Busy Call Return family of service features to be offered by the 3s originating switch to the caller would not be recognized.

This conflict, however, is implementation dependent, as there is no outward difference between this situation and the prototypical situation in which the caller would be offered the Call Busy family of service features.
s Indeed, the invocation of both families of service features are motivated by the same goal, that is, to avoid losing track of the fact of the call and to establish connection between the caller and the recipient at the earliest opportunity and with minimal effort.
io At present, the Call Forward on Busy feature has a penetration of 12% (8.9o for Call Answer feature, 3.1o for Call Forwarding to other DNs) in the residential market, and a penetration of 800 (70o for Call Answer feature, loo for Call Forwarding to other DNs such as secretaries) in the business 15 market. Due to the conflicts stated above, the Busy Call Return family of features cannot be applied to this 12o of residential and 800 of business markets. One variation of the Busy Call Return family is the combination of a message delivery feature described herein, and the EBCR feature. This 2o variation provides a caller with the option of either leaving a message at the originating switch to be forwarded to the intended recipient when the line is no longer busy or of termin<~ting the call attempt with a connection to be automatically established when the intended recipient's line is 2s no longer busy.
While the Busy Call Return family of features cannot at present be applied where the Call Forward on Busy feature resides, presently in 120 of residential and 800 of business market,, it is anticipated that the Call Forward on Busy market 3o share will increase. At present, the majority of those markets, where the Call Forward on Busy feature is not active, have some form of telephone answering device. It is anticipated that more and more of these devices will give way to subscriptions to the Call Answer feature, with the result _ 5 _ that the Call Forward on Busy market share will increase and the applicability of the message delivery/EBCR feature will decrease.
Moreover, the Message Delivery/EBCR service feature s has not gained great customer acceptance because the caller is charged for the privilege of leaving a message for the recipient. Where the recipient's subscribed Call Forward on Busy service is used, no fee is incurred by the caller in leaving a message.
io Thus, the combination of the two families of service features, heretofore unknown, provides a symbiotic relationship, which can be offered to a broad segment of the telecommunications market, whereby the caller is given the opportunity, upon being advised that the intended recipient's i5 line is busy, to do nothing, that is, not to be connected, to have the call forwarded to the DN specified by the recipient, or to arrange for the call to be connected at the earliest opportunity, each of which may be appropriate according to the prevailing circumstances.
2o For instance, the first option is suitable where the impetus for the call requires immediate consultation and any later discussion would be moot. The second option would be appropriate where the caller intends to convey information only and no response from the recipient is required. The last 2s option. otherwise avoids the requirement that the caller leave a message which may have to be repeated or elaborated upon in a subsequent telephone conversation, and the recipient does not need to consult its voice mail. It further avoids the prospect that the original caller's line will be busy when the original 3o recipient attempts to return the his or her call.
SUMMARY OF THE INVENTION
It is desirable to permit the caller to choose whether to have the call forwarded if the intended recipient 3s subscribes to a Call Forward family service feature or be automatically connected at the earliest opportunity if the intended recipient's DN is busy when a call is attempted.
It is also desirable to reduce the possibility of the caller and intended recipient engaging in a circular and s perpetuating cycle of returning each other's calls and only reaching the forwarded destination of the other party.
It is still further desirable to reduce the traffic load on the telecommunications network that would otherwise result from the recipient having to retrieve its messages and io return the caller's call and from the potential that the above-described "telephone tag" cycle would ensue.
The present invention achieves these objects by making use of the features of the Advanced Intelligent Network (AIN) environment for use with Signalling System 7 (SS7 also i5 called Common Channel Signalling 7 or CCS7) telecommunications networks.
The AIN environment is an infrastructure proposed by Bell Communications Research (BellCore) for installation and use by exchange carriers to deploy new services in a quick and 2o effective manner. The AIN environment simplifies the design and implementation of new telecommunication services by defining a set of network elements, messages and call models as standard building blocks. New services may be quickly defined and implemented by a telephone operating company using these 2s standard building blocks. The AIN environment is outlined by Berman et a1. in the ICC '91 proceedings, Volume 2 at pages 21.1.1_ to 21.1.5, June 1991.
More particularly, the AIN environment permits, in one embodiment, the terminating node to overcome the inability 3o inherent in switch-based technology to notify the originating node when the destination DN is busy when one of the Call Forward family of service features is subscribed.
The invention may be summarized according to a broad aspect as in a telecommunications network comprising a 3s plurality of local exchanges connected to customer premises equipment (CPE), a method of processing a call from an originating CPE to a terminating CPE connected by a terminating subscriber line to a node at a local exchange and having message means associated with and accessible to a recipient at the terminating CPE, comprising: setting up a first call across s the network between the originating CPE and the terminating CPE, detecting if the terminating subscriber line is busy so that the first call cannot be completed, not returning a busy indication to the originating CPE if the terminating subsriber line i.s busy, if the terminating subscriber line is busy, to playing an announcement to the originating CPE offering a selection between forwarding the first call to the message means whereby a message may be left or terminating the first call and when the terminating subscriber line subsequently becomes available, setting up a second call across the network i5 between the originating CPE and the terminating CPE, and on receipt of a sequence of at least one dialled digit from the origir_ating CPE, processing the sequence and depending on the sequence either forwarding the first call to the message means or terminating the first call, determining when the terminating 2o subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.
The invention may be summarized according to a second aspect as a telecommunications system for conveying information across a telecommunications network comprising a 2s plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network having an associated originating directory number (DN) within the telecommunications network, to a terminating CPE connected to the telecommunications network 3o by a terminating subscriber line having an associated terminating DN within the telecommunications network, the system comprising: means for establishing a first telecommunications link across the telecommunications network between the originating CPE and the terminating CPE whereby, if 35 the first telecommunications link is established, the information is conveyed directly from the originating CPE to _ g _ the terminating CPE; message means associated with and accessible to a recipient at the terminating CPE; detection means for detecting if the first telecommunications link cannot be established because the terminating subscriber line is busy;
s means for preventing a busy indication from being returned to the orgianting CPE of the terminating subscribe line is busy, selection means for offering if the first telecommunications link cannot be established, a selection between a first option of conveying the information by message io to the message means and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available;
means for establishing a second telecommunications link across the telecommunications network between the originating CPE and is the message means whereby, upon receipt of a first sequence of at least one dialled digit denoting selection of the first option the information is conveyed by message from the originating CPE to the message means; retrieval means for retrieving the message from the message means if the first 20 option was selected; and means for establishing a third telecommunications link across the telecommunications network between the originating CPE and the terminating CPE whereby, upon receipt of a second sequence of at least one dialled digit denoting selection of the second option and upon the 2s terminating subscriber line subsequently becoming available, the information is conveyed directly from the originating CPE
to the terminating CPE.
The invention may be summarized according to third aspect as in a telecommunications system for conveying 3o information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network and having an associated originating directory number (DN), to a terminating CPE connected to the 3s teleco_nmunications network by a terminating subscriber line and having an associated terminating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, a remote processing node for connection with a first node with which the originating DN is associated, with a second node with which the terminating DN is associated, s and with a third node with which a peripheral DN is associated, the remote processing node further comprising logic means which is: responsive to being advised by the second node that a first connection through the first and second nodes between the originating DN and the terminating DN cannot be established io because the terminating subscriber line is busy, for providing the peripheral DN to the second node, whereby a second connection may be established through the first and third nodes between the originating DN and the peripheral DN for a telecommunications device associated with the peripheral DN to i5 offer the originating CPE a selection between a first option of conveying the information by message to a message means associated and accessible to a recipient at the terminating CPE
and having an associated message DN, and a second option of conveying the information directly to the terminating CPE when 2o the terminating subscriber line subsequently becomes available;
responsive to being advised that the first option was selected, for providing the message DN to the second node and issuing a first direction to the second node to establish a third connection through the first and second nodes between the 2s originating DN and the message DN for conveying the information by message from the calls at the originating CPE to the message means for retrieval; responsive to being advised that the second option was selected, for issuing a second direction to monitor the terminating subscriber line and when the 3o terminating subscriber line is no longer busy, to so advise the remote processing node; and responsive to being advised by the second node that the terminating subscriber line is no longer busy, for issuing a third direction to issue a request to establish a fourth connection through the first and second 35 nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPE to the terminating CPE. Software on a computer-readable medium for use in such apparatus is also disclosed.
The invention may be summarized according to a fourth aspect as in a telecommunications system for conveying s information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network at a first node and having an associated originating directory number (DN), to a terminating to CPE connected to the telecommunications network at a second node by a terminating subscriber line having an associated terminating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, a telecommunications device having an associated peripheral DN, i5 for connection with a third node with which the peripheral DN
is associated, the telecommunications device further comprising logic :means, responsive to the establishment of a second connection, through the first and third nodes between the originating DN and the peripheral DN in the event that a first 2o connection through the first and second nodes between the originating DN and the terminating DN cannot be established because the terminating subscriber line is busy, for: offering the originating CPE a selection between a first option of conveying the information by message to a message means 2s associated with and accessible to a recipient at the terminating CPE and having an associated message DN and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available, and providing the selected 30 option to a remote processing node connected to the first, second and third nodes, whereby the remote processing node may, responsive to the selected option, either: direct the second node to establish a third connection through the first and second nodes between the originating DN and the message DN for 3s conveying the information by message from the originating CPE
to the message means for retrieval, or direct the second node to monitor the terminating subscriber line and when the terminating subscriber line is no longer busy, to so advise the remote processing node whereby the remote processing node may direct the establishment of a fourth connection through the s first and second nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPE to the terminating CPE. Software on a computer-readable medium for use in such apparatus is also disclosed.
to The invention may be summarized according to a fifth aspect as in a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), a plurality of service switching point (SSP) nodes at the local exchanges operating with Advanced is Intelligent Network (AIN) applications software and being capable of exchanging Signalling System 7 (SS7) messages with other nodes, a service control point (SCP) node adapted to exchange SS7 messages with other nodes and an intelligent peripheral (IP), a method of processing a call across the 2o network from an originating CPE connected to a first SSP and having an associated originating directory number (DN) to a terminating CPE connected by a terminating subscriber line to a second SSP and having an associated terminating DN, the method comprising the steps of: the first SSP detecting a sequence of 2s dialled digits sent from the originating CPE which denote the terminating DN, the first SSP issuing a first request that a first telecommunications link be established between the originating CPE and the terminating CPE; the second SSP
receiving the first request; the second SSP detecting if the 3o termir_ating subscriber line is busy, so that the first telecommunications link cannot be established; if the terminating subscriber line is not busy, the first and second SSPs establishing the first telecommunications link between the originating and terminating CPEs through the first and second 3s SSPs; the SCP maintaining data identifying the IP, if the terminating subscriber line is busy, the second SSP sending a first information message to the SCP that the terminating subscriber line is busy; the SCP sending a first action request comprising the data identifying the IP to the second SSP, responsive to the first information message, requesting that s the second SSP , using the data, issue a second request that a second telecommunications link be established between the IP
and the originating CPE; the second SSP issuing the second request; a third SSP connected to the IP receiving the second reque:~t; the first and third SSPs establishing the second io telecommunications link between the IP and the originating CPE;
the IP playing an announcement to the originating CPE
across the second telecommunications link, offering a selection to the originating CPE between a first option of forwarding the call t:o a message means, associated with and accessible to a i5 recipient at the terminating CPE whereby a message may be left, or a second option of terminating the call and when the terminating subscriber line subsequently becomes available, establishing a third telecommunications link between the originating and terminating CPEs; on receipt of a second 2o sequence of at least one dialled digit representing the selected option, the IP sending a second information message comprising the selected option to the SCP; the SCP receiving the second information message and examining the selected option; the SCP maintaining data identifying the message means;
2s if the first option was selected, the SCP sending a second action request comprising the data identifying the message means to the second SSP requesting that the second SSP, using the data, establish a fourth telecommunications link through the se~~ond SSP between the originating CPE and the message 3o means; and if the second option was selected: the SCP sending a third action request to the second SSP requesting that the second SSP terminate the first call, the SCP sending a fourth action request to the second SSP requesting that the second SSP
monitor_ the busy/idle status of the terminating subscriber 35 line, the second SSP monitoring the busy/idle status of the terminating subscriber line; when the terminating subscriber line is no longer busy, the second SSP sending a third information message noting this status to the SCP, the SCP, responsive to the third information message, sending a fifth action request to a first node in the network requesting it to s issue a third request that a third telecommunications link be established between the originating CPE and the terminating CPE, the first node issuing the third request, a second node receiving the third request, and the first and second nodes establishing the third telecommunications link between the io originating and terminating CPEs through the first and second nodes.
The invention may be summarized according to a sixth aspect. as a method of processing a call across a telecommunications network comprising a plurality of local i5 exchar_ges connected to customer premises equipment (CPE), from a caller at an originating CPE to an intended recipient at a terminating CPE connected by a terminating subscriber line to a node at a local exchange and having message means associated with and accessible to the intended recipient, comprising the 2o steps of: the caller dialling a sequence of dialled digits at the originating CPE to request that a first call be placed across the network between the originating CPE and the terminating CPE; the network setting up the first call between the originating CPE and the terminating CPE; the network 2s detecting if the terminating subscriber line is busy so that the first call cannot be completed; if the terminating subscriber line is busy, the network playing an announcement to the caller at the originating CPE offering a selection between the network forwarding the first call to the message means 3o whereby a message may be left or the network terminating the first call and when the terminating subscriber line subsequently becomes available, the network setting up a second call a~~ross the network between the originating CPE and the terminating CPE; the caller dialling a second sequence of at 35 least one dialled digit at the originating CPE to select one of the offered selections; on receipt of the second sequence of at least one dialled digit from the originating CPE, the network processing the second sequence and depending on the sequence, either forwarding the first call to the message means or terminating the first call, determining when the terminating s subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.
The invention may be summarized according to a seventh aspect as in a telecommunications network comprising a plurality of local exchanges connected to customer premises io equipment (CPE), a method of processing a caller from an originating CPE to a terminating CPE connected by a terminating subscriber line to a node at the local exchange, comprising:
setting up a first call across the network between the originating CPE and the terminating CPE, detecting if the i5 terminating subscriber line is busy so that the first call cannot be completed, before returning a busy indication to the originating CPE, if the terminating subscriber line is busy, playing an announcement to the originating CPE offering at least a first option of terminating the first call and when the 2o terminating subscriber line subsequently becomes available, setting up a second call across the network between the originating CPE and the terminating CPE, and on receipt of a first sequence of at least one dialled digit from the originating CPE which corresponds to the first option, 2s determining when the terminating subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.
BRIEF DESCRIPTION OF THE DRAWINGS
3o The preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 is a block diagram of a typical SS7 network configuration;
35 FIGURE 2 is a block diagram of a telecommunications system according to the present invention showing the message traffic between network components;
FIGURE 3 is a prior art chart illustrating the events occurring in the originating SSP in placing an outgoing call in the AIN environment;
s FIGURE 4 is a prior art chart illustrating the events occurring in the terminating SSP in placing an outgoing call in the AIN environment; and FIGURE 5 is a flow chart of the service logic for the SCP in accordance with the present invention.
io DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the implementation of the present invention, AIN
(Advanced Intelligent Network) components are used. Various standards exist which apply to AIN networks, the latest North is American version of which is AIN 0.2. Other similar standards exist in Europe and elsewhere. AIN is the latest in a series of developments which have increasingly allowed functionality to be removed from network switches onto separate platforms.
New features or applications can be introduced on an AIN
2o platform with very little impact on the existing network.
AIN makes use of SS7 telecommunications networks, one of which is shown in exemplary fashion in FIGURE 1. The network is implemented on a series of SS7 network nodes 100, 101, 110-113, 120, 121 and partitions the communications 2s traffic into signalling and voice/data components.
The SS7 network nodes are interconnected by signalling links 103-106, 114-119, 122-125. Each SS7 network node contains permanently connected transmitting and receiving equipment to support the signalling links 103-106, 114-119, 30 122-125 which are direct physical connections between two SS7 network nodes 100, 101, 110-113, 120, 121, capable of carrying message traffic at a data rate of either 56 Kbit/s or 64 Kbit/s and comprise a dedicated signalling path to carry the signalling components in message form between the SS7 network 3s nodes 100, 101, 110-113, 120, 121.

. - 16 -One type of SS7 network node is the service switching point (SSP) 100, 101. The SSPs 100, 101 are telephone switches which provide telephony services. They are interconnected by voice trunks 102 along which the voice/data components are s passed. An example of an SSP 100, 101 switch is the Digital Multiplex Switch (DMSTM) manufactured by Nortel. In an AIN-capable SS7 network, the SSP 100, 101 has an enhanced instruction and message set which permits AIN functionality when used with other AIN-capable SS7 network nodes.
io The SSP 100, 101 hosts a plurality of subscriber lines 132, 133 each of which is capable of connection to customer premises equipment (CPE) apparatus 130, 131, such as a telephone handset, a telephone answering machine, a private branch exchange, a computer modem or a fax machine.
15 Alternatively, an AIN-capable intelligent peripheral (IP) 1.40 may be connected to an SSP 100, 101 by PRI trunks, 141. An IP 140 is an intelligent telecommunications device which provides capabilities for the playback of prompts or announcements, long- and short-term message recording, DTMF
2o digit collection and detection, DTMF tone generation, message compression, call control and voice recognition. The IP 140 is application independent and its capabilities can be used by multiple applications.
Each of the subscriber lines may be assigned a unique 2s 10 digit network directory number (DN) by which the line itself is identified.
The other types of SS7 network node are the signalling transfer point (STP) 110-113 and the service control point (SCP) 120, 121. The SSPs 100, 101, SCPs 120, 121 and 3o STPS 110-113 in a network are interconnected by signalling links 103-106, 114-119, 122-125.
The STPs 110-113 are packet switches responsible for receiving messages along its signalling links 103-106, 114-119, 122-125 from other network nodes 100, 101, 110-113, 120-121 and 35 routing the messages to the appropriate destination network node 100, 101, 110-113, 120-121. The STPs 110-113 act as signalling message hubs which reduce the number of point to point signalling links 103-106, 114-119, 122-125 which must otherwise be created to interconnect the SSPs 100, 101 and SCPs 120, 121 in a network.
s To ensure network availability, STPs 110-113 are customarily deployed in mated pairs. STPs 110-113 in a mated pair are connected to the same set of network nodes 100, 101, 110-113, 120-121, perform identical functions, are redundant and are effectively transparent. Thus, if problems develop in to one STP (for example 112), the mated STP (in the example, 113;
would provide an uninterrupted transfer of messages to all concerned nodes 100, 101, 110-113, 120-121 in the network. In Figure l, STPs 110 and 111 and STPs 112 and 113 are mated pair sets.
15 As indicated previously, the STPs 110-113 act as hubs and are effectively transparent in operation. Thus, it is immaterial how a message is passed among SSPs 100, 101 and SCPs 120,121, for example, whether the message is physically transmitted from SSP 100 along signalling link 103 to STP 110, 2o thence along signalling link 115 to STP 112 and thence along signalling link 122 to SCP 120, or from SSP 100 along signalling link 104 to STP 111, thence along signalling link 118 to STP 113 and thence along signalling link 125 to SCP 120.
The SCP 120, 121 is a remote processing node in the 2s SS7 network which houses databases with call routing information for advanced telecommunications services such as 800 number service, credit card validation, Centrex and local number portability as well as software to access these databases. To ensure network availability, SCPs 120, 121 are 3o also customarily deployed in mated pairs. In the Figure, SCPs 120 and 121 comprise a mated pair set. In an AIN-capable SS7 networ,s, the SCP 120, 121 has an enhanced instruction and message set which permits AIN functionality when used with other AIN-capable SS7 network nodes.
35 There are two types of signalling messages, both of which may be passed along the signalling links 103-106, 114-119, 122-125 between SS7 network nodes 100, 101, 110-113, 120, 121. The first type of signalling message (known as ISDN User Part or ISUP) provides basic call routing by controlling the call setup for the various voice trunks 102 passing between s SSPs 100, 101. A single signalling link 103-106, 114-119, 122-125 may thus be used to manage the call control for a large number of voice/data components.
The second type of signalling message (known as transactions capability applications part or TCAP) comprises to the set of request, response and control messages and associated procedures that enable one SSP 100, 101 to initiate a transaction on another SSP 100, 101.
In an SS7 network, an SSP 100, 101 may, during the course of a call, stop at a number of defined detection points, i5 (DP) to obtain information on how to proceed with the call processing. Such information is obtained by an SSP 100, 101 by the exchange of messages to and from an SCP 120, 121. Upon reaching a DP, the SSP 100, 101 suspends processing and sends a query message to the SCP 120, 121. The SCP 120, 121, upon 2o receiving a query message from an SSP 100, 101, combines a large consolidated database and the service logic required to access and use the data contained therein to apply call services. The SCP 120, 121 will then either instruct the SSP
100, 1.01 to continue with normal call processing, or override 2s normal call processing and perform specific actions such as (i) collect more digits, (ii) route the call to a new DN, (iii) route the call using a specific route list, or (iv) play an announcement. The instructions provided by the SCP 120, 121 to the SSP 100, 101 are in the form of signalling messages. The 3o SCP 120, 121 may also provide instructions to an SSP (say 101) other than the SSP (say 100) which originated the query, in order to request that the SSP 101 initiate a transaction downstream.
An SS7 network which has AIN capability makes use of 35 the signalling links 103-106, 114-119, 122-125 in an SS7 network in conjunction with a standardized signalling protocol defined between the SSPs 100, 101 and the SCPs 120, 121 using an enhanced set of TCAP messages which is the same for any feature or application.
Under the AIN protocol, when an SSP 100, 101 s encounters a DP and suspends processing, AIN-specific 'triggers' are used to determine whether or not to send a message to an SCP 120, 121 to invoke the service logic associated with the DP. At each DP, a call is checked for subscriptions to triggers, that is, a list of conditions which io must be met before an AIN message is sent. Depending upon the subscribed services, there may be one or more triggers at each DP.
When a subscribed trigger is found, details of the call are checked against the criterion list associated with the 15 trigger. If all criteria are satisfied, the SSP 100, 101 generates a query to the SCP 120, 121 and suspends call processing until instructions from the SCP 120, 121 are received. Typically, subsequent call processing for that call will be influenced by the instruction provided by the SCP 120, 20 121 .
Upon receipt of the query message, the SCP 120, 121 will access its database tables and construct a call control message that is returned to the triggering SSP 100, 101 along the signalling links 103-106, 114-119, 122-125 extending 2s between them.
The SSP 100, 101 will then use the call control message to complete the call through the network.
Thus, the introduction of a new AIN feature requires the definition of an AIN trigger and the allocation of database 3o memory at the SCP 120, 121 and the introduction of service logic at the SCP 120, 121 to implement the feature.
Referring now to FIGURE 2, a block diagram is shown of the message flow in a telecommunications system whereby an Integrated Call Forward/Enhanced AIN Call Busy feature may be 35 implemented according to an embodiment of the invention. The system illustrated includes components for a caller to place an outgoing call to an intended recipient, components for the intended recipient to receive the incoming call and components for the establishment of a connection between the caller and the recipient. Typically, the caller and the intended s recipient could be any person capable of connection to the teleccmmunications network in which the feature is implemented.
The components for placing the outgoing call include a conventional originating CPE 200 connected to an originating local exchange 204. The connection between the originating CPE
io 200 and the originating local exchange 204 is shown in exemplary fashion in Figure 2 by an originating subscriber line 201. Depending upon the configuration of the caller's telecommunications system, the connection with the originating local exchange 204 may comprise the originating subscriber line i5 201 connected to a switch which may form part of the caller's company network (eg. PBX) and a subscriber line or trunk to the originating local exchange 204. An originating DN 202 is associated with the originating subscriber line 201.
The point of access to the originating local exchange 20 204 of the originating CPE 201 may be an originating SSP 206 as shown in exemplary fashion in Figure 2, or, depending upon the configuration of the originating local exchange 204, may be an access node which is itself ultimately connected to the originating SSP 206. The originating SSP 206 is AIN-capable.
2s The components for receiving the intended call includE= a conventional terminating CPE 250 connected to a terminating local exchange 254. The terminating local exchange 254 may be identical to the originating local exchange 204.
The connection between the terminating CPE 250 and the 3o terminating local exchange 254 is shown in exemplary fashion in Figure 2 by a terminating subscriber line 251. Depending upon the configuration of the recipient's telecommunications system, the connection with the terminating local exchange 254 may comprise the terminating subscriber line 251 connected to a 35 switch which may form part of the recipient's company network (eg. PBX) and a subscriber line or trunk to the terminating local exchange 254.
A terminating DN 252 is associated with the terminating subscriber line 251. A voice mailbox 280 s associated with the terminating DN 252 is connected by a voice mailbox line 281, which may be a PRI trunk or a voice trunk, with a mailbox SSP 286. A mailbox DN 282 is associated with the voice mailbox line 281.
It will be apparent to those skilled in the art that to the voice mailbox 280 may alternatively comprise a separate CPE
with an associated subscriber line and forwarding DN. In such a case, the terminating DN 252 will be programmed to forward some or all calls directed to it to the mailbox DN 282. The associated subscriber line may not be directly connected to the 15 terminating SSP 256, depending upon the location of the separate CPE. Additionally, although shown in exemplary fashion as part of the terminating local exchange 254, the voice mailbox 280 may be part of the originating local exchange 204 or some other local exchange (not shown).
2o The point of connection to the terminating local exchange 254 of the terminating CPE 250 may be a terminating SSP 256 as shown in exemplary fashion in Figure 2, or, depending upon the configuration of the terminating local exchange 254, may be an access node which is itself ultimately 25 connected to the terminating SSP 256. The terminating SSP 256 is AIN-capable.
The components for establishing a connection between the originating CPE 200 and the terminating CPE 250 include an AIN-capable SCP 230 which may be part of the originating local 3o exchange 204 as shown in exemplary fashion in Figure 2 (or the terminating local exchange 254 or neither), the originating SSP
206, the terminating SSP 256 and a peripheral SSP 246 which may form part of the originating local exchange 254 as shown in exemplary fashion in Figure 2 and an IP 240.
35 The connection between the IP 240 and the originating local exchange 204 is shown in exemplary fashion in Figure 2 by peripheral PRI trunks 241. A peripheral DN 242 is associated with the peripheral PRI trunks 241.
Depending upon the location of the originating CPE
200, the terminating CPE 250, the voice mailbox 280 and the IP
s 240, two or more of the originating SSP 206, the terminating SSP 256, the mailbox SSP 286 and the peripheral SSP 246 may be the same. Alternatively, any or all of the originating CPE
200, the terminating CPE 250, the voice mailbox 280 and the IP
240 may be serviced by more than one SSP. Further, the io functionality of the SCP 230 may be split over or duplicated in more than one SCP.
It will also be apparent to those skilled in the art that there may be 0 or more STP mated pairs 220 interconnecting the originating SSP 206, the terminating SSP 256, the is peripheral SSP 246 and the SCP 230 depending upon the network configuration. These interconnections have been omitted for clarity of Figure 2.
In operation, the caller dials the terminating DN 252 at the originating CPE 200. The dialled digits are transmitted 2o to the originating SSP 206 along the originating subscriber line 201 where it is processed.
The originating SSP 206 processes the dialled digits and attempts to set up a call along voice trunks 102 (not shown) between it and the destination SSP 256 and eventually to 2s the terminating CPE 250.
If the terminating DN 251 is busy, the terminating SSP 256 does not return a busy signal to the originating SSP
206. Rather the terminating SSP 256 so notifies the SCP 230, which directs the terminating SSP 256 to connect the 30 originating CPE 200 with the IP 240 through the peripheral SSP
246. The IP 240 plays an announcement prompting the caller to select between either leaving a message on the voice mailbox 258 associated with the terminating DN 252 or being connected with the terminating CPE 250 when the terminating DN 252 is no 35 longer busy or being forwarded to another CPE. The IP 240 returns the choice selected by the caller to the terminating SSP 25~, which notifies the SCP 230. The caller may, alternatively, simply place the originating CPE 200 on-hook with the intention of thus becoming disconnected.
If the caller chooses to leave a message on the voice s mailbox 258 associated with the terminating DN 252, upon being so notified, the SCP 230 directs the terminating SSP 256 to connect the originating CPE 200 with the voice mailbox 258.
If the caller places the originating CPE 200 on-hook, the attempted call is terminated.
io If the caller chooses to be connected with the terminating CPE 250 when the terminating DN 252 is no longer busy, upon being so notified, the SCP 230 updates its database and directs the terminating SSP 256 to terminate the call attempt. The SCP 230 then arranges for a call to be connected i5 between the originating CPE 200 and the terminating CPE 250 when the terminating DN 252 is no longer busy.
In the preferred embodiment, this is accomplished by the SCl? 230 instructing the terminating SSP 256 to monitor the terminating DN 252 and to notify the SCP 230 when it is no 20 longer busy. The SCP 230 thereupon requests the originating SSP 205 to set up a call between the originating CPE 200 and the terminating CPE 250 along the originating SSP 200 and the terminating SSP 250. Alternatively, the SCP 230 could request the terminating SSP 256 to set up the call.
25 FIGURE 3 sets out the originating basic call model (BCM), which is Figure 3-4 from BellCore Standard GR-1298-CORE, Issue 3, July, 1996, and is described in paragraph 3.2, being well known in the art. The originating BCM is a program resident on all SSPs which identifies ten points in call 30 (originating PICs) 301-310 representing stages in the processing of an outbound call by an SSP, such as by the originating SSP 206 in the present invention. The originating BCM also identifies a number of originating DPs 311-337 between originating PICs 301-310 at which the SCP can receive 35 notification of a given event and influence subsequent call processing.

Certain originating DPs 311-337 are identified as originating trigger detection points (TDPs) 322-332.
Originating TDPs 322-332 may be active or inactive. A
particular originating TDP 322-332 may be activated or s deactivated for a particular network, subscriber or call.
Other originating DPs 311-337 are identified as originating event detection points (EDPs) 325-337. An originating DP 311-337 ma:y be both an originating TDP 322-332 and an originating DP 325-337. When an originating TDP 322-332 is active or an io originating EDP 325-337 is reached and the event occurs, normal call processing by the SSP at the originating end is interrupted and a query is made to the SCP. The response from the SCP may or may not alter the balance of the call processing. One of the possible responses is to arm events on i5 a call basis.
FIGURE 4 sets out the terminating BCM, which is Figure 3-5 from BellCore Standard GR-1298-CORE, Issue 3, July, 1996, and is described in paragraph 3.3, being well known in the art. The terminating BCM is a program resident on all SSPs 2o which identifies seven terminating PICs 401-407 representing stages in the processing of an inbound call by an SSP, such as by the terminating SSP 256 in the present invention. The terminating BCM also identifies a number of terminating DPs 408-421 between terminating PICs 401-407 at which the SCP can 2s receive notification of a given event and influence subsequent call processing.
Certain terminating DPs 408-421 are identified as terminating TDPs 415-419. Terminating TDPs 415-410 may be active or inactive. A particular terminating TDP 415-419 may 3o be activated or deactivated for a particular network, subscriber or call. Other terminating DPs 408-421 are identified as terminating EDPs 416-421. A terminating DP 408-421 may be both a terminating TDP 408-419 and a terminating EDP
416-42:L. When a terminating TDP 408-419 is active or a 35 terminating EDP 416-421 is reached and the event occurs, normal call processing by the SSP at the terminating end is interrupted and a query is made to the SCP. The response from the SCP may or may not alter the balance of the call processing. One of the possible responses is to arm events on a call basis.
s The originating BCM and the terminating BCM provide for the exchange of a series of call setup messages between the SSP at the originating end and the SSP at the terminating end using ISUP messages 261.
The present invention requires the activation of the io T_Busy trigger, which is assigned to the terminating subscriber lien 251, at the (e30) T_Busy TDP 417 of the terminating BCM.
The T-Busy trigger is defined in the BellCore Standard GR-1298-CORE, Issue 3, July, 1996, at paragraph 4.2.3.3, which provides that the trigger will be encountered when the SSP at the i5 terminating side determines that the DN to which the incoming call is directed is busy.
Referring again to Figure 2, upon encountering the T Busy trigger, the terminating SSP 256 does not provide a busy indication to the originating SSP 206 (which conventionally 2o would involve the transmission of a Release message with a Busy cause to the originating SSP 206), but rather sends a T_Busy TDP-Request message 262 to the SCP 230, containing the originating DN 202, the destination DN 252 and Bearer Capability, which identifies the call as comprising speech, 2s audio or data. This message is defined in the BellCore Standard GR-1298-CORE, Issue 3, July, 1996, at paragraph 4.5.4.3.
The service logic followed by the SCP 230 is shown in flow chart form in Figure 5. If the SCP 230 determines 500 3o that it has received a T-Busy TDP-Request message 262, it determines, from the originating DN 202 contained in the message parameters, whether or not the caller has subscribed to the service feature incorporating the present invention 510.
If the SCP 230 determines 510 that the caller has not 35 subscribed to the service feature incorporating the present invention, subsequent call processing 515-519 is handled in a conventional manner in accordance with the service feature or features, if any, to which the intended recipient has subscribed. That is, if the intended recipient has neither the Call Answer nor the Call Forward on Busy service features s subscribed, the SCP 230 sends a Continue message 516 to the terminating SSP 256. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.2.6, and directs the terminating SSP 256 to resume its normal call processing in accordance with the terminating BCM. In this io case, because the terminating SSP 256 detected a busy condition with respect to the terminating DN 252, it returns a Release message (not shown) to the originating SSP 206 with a busy cause. This message is defined in BellCore Standard GR-317-CORE, Issue l, Revision 3, November 1996, at paragraph 3.1.3.1 is and causes the originating SSP 206 to return a busy signal to the originating CPE 200 in accordance with the originating BCM, whereupon the caller will place the originating CPE 200 on-hook and terminate the call attempt.
If the intended recipient has subscribed to either 2o the Call Answer or the Call Forward on Busy service features, the SCP 230 sends a Forward_Call message 518-519 with a DN to the terminating SSP 256. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.2.2 and directs the terminating SSP 256 to redirect the call to the 2s DN specified in the message. In the preferred embodiment shown in Figure 2, the subscribed service feature is Call Answer and the DN is the mailbox DN 282, so that the caller is given an opportunity to leave a message with the intended recipient's voice mailbox 280. If the subscribed service feature is Call 3o Forward on Busy, the forwarding DN will be the DN specified by the intended recipient when the feature is activated and the call would have the opportunity to speak with anyone answering the CPE attached to the subscriber line associated with the forwarding DN. In the event that the intended recipient 3s subscribes to both the Call Answer and the Call Forward on Busy service features, the determination of which service feature governs is made in accordance with guidelines specified in the imple~r,entation of these service features. In Figure 5, the Call Forward or Busy service feature is shown in exemplary fashicn to govern. In all cases, the SSP associated with the s mailbox DN 282 or the forwarding DN as the case may be would thereupon resume processing in accordance with the terminating BCM as if the DN specified in the message were the destination of the call.
If the SCP 230 determines 510 that the caller has to subscribed to the service feature incorporating the present invention, the SCP 230 determines 520, from the terminating DN
252, whether or not the intended recipient has subscribed to either a Call Answer service feature or a Call Forward on Busy service feature or both and which of these features is active.
15 The SCP 230 then sends a Send-To-Resource message 263 with the peripheral DN 242 to the terminating SSP 256. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996 at paragraph 5.5, and provides that the terminating SSP
256, upon receipt of the message, will direct the incoming call 2o from the originating CPE 200 via the originating SSP 206 to the IP 240 via the peripheral SSP 246. The terminating SSP 256 sends an IAM message 264 to the peripheral SSP 246. The IAM
message 264 is an ISUP message with a remote operation (RO) parameter containing the information received from the SCP 230 2s in the Send-To_Resource message 263.
If the peripheral DN 242 is available, a call 265 is set up and the caller at the originating CPE 200 is connected to the IP 240 through the originating SSP 206 and the peripheral SSP 246. The call 265 will make use of voice trunks 30 102 (not shown) to which the originating SSP 206 is connected and to which the peripheral SSP 246 is also connected. Those familiar with the art will readily recognize that the transmission path for the call 265 may pass along more than one voice trunk 102 (not shown) between the originating SSP 206 and 35 the peripheral SSP 256 and through additional SSPs (not shown) depending upon the network configuration.

During the call 265, the IP 240 plays a predetermined message prompting the caller to select, by dialling a digit, between a number of service options. The message played and the options provided thereby is determined by which service s features, if any, the intended recipient has subscribed. In all cases, one of the options (EBCR option), is for the call to be terminated and a new call connected between the originating CPE 200 and the terminating CPE 250 when the terminating subscriber line 251 is no longer busy. If the intended io recip:ient has subscribed to the Call Answer service feature, an additional option (CA option) is offered to the caller, whereby the call will be forwarded to the intended recipient's voice mailbox 258. If the intended recipient has subscribed to the Call Forward on Busy service feature, a further option (CF
15 option) is offered to the caller, whereby the call will be forwarded to the DN specified by the intended recipient in activating this feature. The caller always has the option of not selecting any of these options by placing the originating CPE 200 on-hook, thus terminating the call in the conventional 2o fashion.
The peripheral SSP 246 will collect any digit dialled in response to the message and forward the collected digit to the terminating SSP 256 in an FAC message 266 which is also an ISUP message with an RO parameter comprising the collected 2s digit .
The terminating SSP 256 sends a Call-Info-From_Resource message 267 containing the collected digit to the SCP 230. This message is defined in BellCore Standard GR-1129-CORE, Issue 3, July 1996 at paragraph 4. If 3o the SCP 230 determines 505 that such a message has been received by it, it processes the collected digit and determines 525 whether or not the digit is valid, that is, whether or not it corresponds to one of the available options. If the digit is not valid, the SCP 230 initiates error recovery processing 35 in a conventional fashion, which may include a predetermined number of retry attempts 530-532.

If the SCP 230 determines 525 that the digit is valid, it sends a Call-Info-To_Resource message 268 to the terminating SSP 256 instructing it to arrange for the termination of the call 265. The terminating SSP 256 then s sends an FAC message 269 to the peripheral SSP 246, whereupon the peripheral SSP 246 disconnects the originating SSP 206 from the IP 240, thus terminating the call 265. Upon disconnection, the terminating SSP 256 sends a Resource_Clear message 270 to the SCP 230. This message is defined in BellCore Standard GR-io 1298-CORE, Issue 3, July 1996 at paragraph 5.5.1.5 and indicates that the connection between the caller at the originating CPE 200 and the IP 240 has been disconnected.
Once the SCP 230 determines 535 that such a message has been received, it determines 540,545 from the dialled digit i5 which option was selected. If the SCP 230 determines 545 that the caller selected the CA or CF option, the SCP 230 sends a Forwaz-d_Call message with the mailbox DN 282 (in the case of the CA option being selected 546) or the forwarding DN
specified by the intended recipient (in the case of the CF
20 option being selected 547) to the terminating SSP 256. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.2.2, and directs the terminating SSP
256 to redirect the call to the DN specified in the message.
In either event, the SSP associated with the forwarded DN, 2s whether the mailbox DN 259, or otherwise, would thereupon resume processing in accordance with the terminating BCM as if the forwarded DN were the destination of the call.
If the SCP 230 determines 540 that the caller selected the EBCR option, the SCP 230 sends a Disconnect 3o message 271 to the terminating SSP 256. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996 at section 5.2.7 and instructs the terminating SSP 256 to terminate the call attempt, in accordance with the terminating BCM. ~his results in an ISUP REL message 272 to the originating SSP 206 and causes the originating SSP 206 to clear the line, this terminates the call in accordance with the originating BCM.
The SCP 230 then sends a Monitor_For-Change message s 273 to the terminating SSP 256. This is a non-call associated message that is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.6 and instructs the terminating SSP 256 to monitor the busy/idle status of the terminating DN 252. Upon determining that the terminating DN
l0 252 is idle, the terminating SSP 256 will send a Statua-Reported message 274 to the SCP 230 to advise it of this fact. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.6.
If the SCP 230 determines 550 that it received such a is message, it thereupon sends a Create-Call message 275 to the originating SSP 206. This message is defined in BellCore Standard GR-1298-CORE, Issue 3, July 1996, at paragraph 5.9, and provides that the originating SSP 206, upon receipt of the message, will exchange call set up messages 276 with the 2o terminating SSP 256 to set up a call between the originating CPE 200 and the terminating CPE 250, in accordance with the originating BCM, in the case of the originating SSP 206 and the terminating BCM, in the case of the terminating SSP 256.
Thus, the caller at the originating CPE 200 and the 2s recipient at the terminating CPE 250 will be able to communicate along a voice trunk 102 (not shown) to which the originating SSP 206 is connected and to which the terminating SSP 256 is also connected until the call is terminated in the conventional fashion in accordance with the originating BCM and 3o the terminating BCM. Those familiar with the art will readily recognize that the transmission path may pass along more than one voice trunk 102 (not shown) between the original SSP 206 and the terminating SSP 256 and through additional SSPs (not shown) depending upon the network configuration.
35 It will be apparent to those skilled in the art that where the intended recipient has neither the Call Answer service feature nor the Call Forward or Busy service feature subscribed and active, the present invention resolves to an AIN
implementation of the EBCR service feature described above, as neither the CA option nor the CF option will be offered to the s caller in the message played by the IP. It will be further apparent that the EBCR option, when selected by the caller, whether as part of a menu of options as described in the preferred embodiment or on its own as described herein, may alternatively be implemented using conventional switched-based io technology without reliance on AIN functionality.
While the preferred embodiment of the present invention has been described and illustrated it will be apparent to one skilled in the art that variations in the design may be made. The scope of the present invention, is therefore, is only to be limited by the claims appended hereto.

Claims

1. In a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), a method of processing a call from an originating CPE to a terminating CPE connected by a terminating subscriber line to a node at a local exchange and having message means associated with and accessible to a recipient at the terminating CPE, comprising:
setting up a first call across the network between the originating CPE and the terminating CPE, detecting if the terminating subscriber line is busy so that the first call cannot be completed, not returning a busy indication to the originating CPE if the terminating subscriber line is busy, if the terminating subscriber line is busy, playing an announcement to the originating CPE offering a selection between forwarding the first call to the message means whereby a message may be left or terminating the first call and when the terminating subscriber line subsequently becomes available, setting up a second call across the network between the originating CPE and the terminating CPE, and on receipt of a sequence of at least one dialled digit from the originating CPE, processing the sequence and depending on the sequence either forwarding the first call to the message means or terminating the first call, determining when the terminating subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.

2. A method according to claim l, in which the step of setting up the first call further comprises the steps of:
detecting, at a first node in the network connected to the originating CPE, a sequence of dialled digits sent from the originating CPE and denoting a terminating directory number (DN) associated with the terminating subscriber line;
the first node issuing a request that a telecommunications link be established between the originating CPE and the terminating CPE;
a second node in the network connected by the terminating subscriber line to the terminating CPE receiving the request;
and if the terminating subscriber line is available, the first and second nodes establishing the telecommunications link between the originating and terminating CPEs through the first and second nodes.

3. A method according to claim 1, in which the step of playing an announcement further comprises the steps of:
a remote processing node in the network maintaining data identifying a telecommunications device connected to the network;
a first node in the network connected by the terminating subscriber line to the terminating CPE sending an information message to the remote processing node that the terminating subscriber line is busy;
the remote processing mode sending an action request comprising the data to the first node, responsive to the information message, requesting the first node to issue a request that a telecommunications link be established between the telecommunications device and the originating CPE;
the first node issuing the request;
a second node connected to the telecommunications device receiving the request;
the second node and a third node connected to the originating CPE establishing the telecommunications link between the telecommunications device and the originating CPE
through the second and third nodes; and the telecommunications device playing the announcement to the originating CPE across the telecommunications link.

4. A method according to claim 1, in which the step of processing the sequence of at least one dialled digit further comprises the steps of:
a telecommunications device connected to the network receiving the sequence from the originating CPE across a telecommunications link established through a first node in the network connected to the originating CPE and a second node in the network connected to the telecommunications device;
the telecommunications device sending an information message comprising the sequence to a remote processing node in the network; and the remote processing node examining the sequence.

5. A method according to claim 1, in which the step of forwarding the first call further comprises the steps of:
a remote processing node in the network maintaining data identifying the message means;
the remote processing node sending an action request comprising the data to a node in the network connected by the terminating subscriber line to the terminating CPE, responsive to the sequence of at least one dialled digit, requesting the node to establish a telecommunications link using the data, through the node between the originating CPE and the message means; and the node establishing the telecommunications link between the originating CPE and the message means through the node.

6. A method according to claim 1, in which the step of determining when the terminating subscriber line is no longer busy further comprises the steps of:
a remote processing node in the network sending an action request to a node in the network connected by the terminating subscriber line to the terminating CPE and requesting the node to monitor the busy/idle status of the terminating subscriber line;
the node monitoring the busy/idle status of the terminating subscriber line; and when the terminating subscriber line is idle, the node sending an information message noting this status to the remote processing node.

7. A method according to claim 1, in which the step of setting up the second call further comprises the steps of:
a remote processing node in the network sending an action request to a first node in the network requesting it to issue a request that a telecommunications link be established between the originating CPE and the terminating CPE;
t:he first node issuing the request;
a second node receiving the request; and the first and second nodes establishing the telecommunications link between the originating CPE and the terminating CPE through the first and second nodes.

8. A method according to claim 7, in which the first node is connected to the originating CPE and the second node is connected by the terminating subscriber line to the terminating CPE.

9. A method according to claim 7, in which the second node is connected to the originating CPE and the first node is connected by the terminating subscriber line to the terminating CPE.

10. A method according to claim 1, in which the message means comprises a voice mailbox connected to the network.

11. A method according to claim 1, in which the message means comprises a forwarding CPE connected to the network.

12. A telecommunications system for conveying information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network having an associated originating directory number (DN) within the telecommunications network, to a terminating CPE
connected to the telecommunications network by a terminating subscriber line having an associated terminating DN within the telecommunications network, the system comprising:
means for establishing a first telecommunications link across the telecommunications network between the originating CPE and the terminating CPE whereby, if the first telecommunications link is established, the information is conveyed directly from the originating CPE to the terminating CPE;
message means associated with and accessible to a recipient at the terminating CPE;
detection means for detecting if the first telecommunications link cannot be established because the terminating subscriber line is busy;
means for preventing a busy indication from being returned to the originating CPE if the terminating subscriber line is busy, selection means for offering if the first telecommunications link cannot be established, a selection between a first option of conveying the information by message to the message means and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available;
means for establishing a second telecommunications link across the telecommunications network between the originating CPE and the message means whereby, upon receipt of a first sequence of at least one dialled digit denoting selection of the first option the information is conveyed by message from the originating CPE to the message means;
retrieval means for retrieving the message from the message means if the first option was selected; and means for establishing a third telecommunications link across the telecommunications network between the originating CPE and the terminating CPE whereby, upon receipt of a second sequence of at least one dialled digit denoting selection of the second option and upon the terminating subscriber line subsequently becoming available, the information is conveyed directly from the originating CPE to the terminating CPE.

13. A telecommunications system according to claim 12, in which the means for establishing the first telecommunications link further comprises:
a first node, connected to the originating CPE and comprising means for detecting a third sequence of dialled digits sent from the originating CPE which denote the terminating DN and for issuing a request that the first telecommunications link be established; and a second node, connected to the terminating CPE and comprising means for receiving the request and if the terminating subscriber line is available, for establishing the first telecommunications link through the first and second nodes between the originating CPE and the terminating CPE.

14. A telecommunications system according to claim 12, in which the detection means further comprises a node connected to the terminating CPE and comprising means for detecting whether the terminating subscriber line is busy.

15. A telecommunications system according to claim 12, in which the selection means further comprises:
a telecommunications device for offering a selection between the first and second options;
means for establishing a fourth telecommunications link between the originating CPE and the telecommunications device whereby the request can be conveyed;
a remote processing node for obtaining and processing the sequence of dialled digits denoting selected option; and means for providing the selected option to the remote processing node.

16. A telecommunications system according to claim 14, in which the means for establishing the fourth communications link further comprises:
a first node connected to the originating CPE;
a second node connected to the terminating CPE and comprising means for sending an information message to the remote processing node that the terminating subscriber line is not available;
means at the remote processing node for maintaining, accessing and communicating telecommunications device identification data to the second node in an action request responsive to the information message;
means at the second node, in response to the action request, for receiving the telecommunications device identification data and issuing a request using the telecommunications device identification data that the fourth telecommunications link be established; and a third node connected to the telecommunications device and comprising means for receiving the first request and for establishing the fourth telecommunications link through the first and third nodes between the originating CPE and the telecommunications device.

17. A telecommunications system according to claim 12, in which the means for establishing the second telecommunications link further comprises:
a first node connected to the originating CPE;
a remote processing node comprising means for maintaining, accessing and communicating message means identification data by which the second telecommunications link between the originating CPE and the message means may be established; and a second node connected to the terminating CPE and comprising means for receiving the message means identification data from the remote processing node and for establishing the second telecommunications link using the message means identification data through the first and second nodes between the originating CPE and the message means.

18. A telecommunications system according to claim 12, in which the retrieval means comprises means for establishing a fourth telecommunications link across the telecommunications network whereby the message can be retrieved.

19. A telecommunications system according to claim 12, in which the means for establishing the third telecommunications link further comprises:
a first node connected to the originating CPE;
a remote processing node comprising means for issuing a first action request to a second node connected to the terminating CPE, to monitor the terminating subscriber line;
means at the second node, responsive to the first action request, for monitoring the terminating subscriber line and for sending an information message to the remote processing node when the terminating subscriber line becomes available; and requesting means at the remote processing node, responsive to the information message, for requesting the establishment of the third telecommunications link.

20. In a telecommunications system for conveying information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network and having an associated originating directory number (DN), to a terminating CPE connected to the telecommunications network by a terminating subscriber line and having an associated terminating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, a remote processing node for connection with a first node with which the originating DN is associated, with a second node with which the terminating DN is associated, and with a third node with which a peripheral DN is associated, the remote processing node further comprising logic means which is:
responsive to being advised by the second node that a first connection through the first and second nodes between the originating DN and the terminating DN cannot be established because the terminating subscriber line is busy, for providing the peripheral DN to the second node, whereby a second connection may be established through the first and third nodes between the originating DN and the peripheral DN for a telecommunications device associated with the peripheral DN to offer the originating CPE a selection between a first option of conveying the information by message to a message means associated and accessible to a recipient at the terminating CPE
and having an associated message DN, and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available;
responsive to being advised that the first option was selected, for providing the message DN to the second node and issuing a first direction to the second node to establish a third connection through the first and second nodes between the originating DN and the message DN for conveying the information by message from the calls at the originating CPE to the message means for retrieval;
responsive to being advised that the second option was selected, for issuing a second direction to monitor the terminating subscriber line and when the terminating subscriber line is no longer busy, to so advise the remote processing node; and responsive to being advised by the second node that the terminating subscriber line is no longer busy, for issuing a third direction to issue a request to establish a fourth connection through the first and second nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPE to the terminating CPE.

21. The invention according to claim 20, in which the remote processing node is a service control point (SCP) adapted to exchange Advanced Intelligent Network (AIN) messages with other nodes.

22. The invention according to claim 20, in which the remote processing node is an adjunct node adapted to exchange Advance Intelligent Network (AIN) messages with other nodes and the first, second and third nodes are the same.

23. In a telecommunications system for conveying information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network at a first node and having an associated originating directory number (DN), to a terminating CPE connected to the telecommunications network at a second node by a terminating subscriber line having an associated termir_ating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, a telecommunications device having an associated peripheral DN, for connection with a third node with which the peripheral DN is associated, the telecommunications device further comprising logic means, responsive to the establishment of a second connection, through the first and third nodes between the originating DN and the peripheral DN in the event that a first connection through the first and second nodes between the originating DN and the terminating DN cannot be established because the terminating subscriber line is busy, for:
offering the originating CPE a selection between a first option of conveying the information by message to a message means associated with and accessible to a recipient at the terminating CPE and having an associated message DN and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available, and providing the selected option to a remote processing node connected to the first, second and third nodes, whereby the remote processing node may, responsive to the selected option, either:
direct the second node to establish a third connection through the first and second nodes between the originating DN and the message DN for conveying the information by message from the originating CPE to the message means for retrieval, or direct the second node to monitor the terminating subscriber line and when the terminating subscriber line is no longer busy, to so advise the remote processing node whereby the remote processing node may direct the establishment of a fourth connection through the first and second nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPE to the terminating CPE.

24. The invention according to claim 23, in which the telecommunications device is an intelligent peripheral (IP) for use in. an Advanced Intelligent Network (AIN) system.

25. In a telecommunications system for conveying information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network and having an associated originating directory number (DN), to a terminating CPE connected to the telecommunications network by a terminating subscriber line and having an associated terminating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, software on a computer-readable medium for use in a remote processing node, for connection with a first node with which the originating DN is associated, with a second node with which the terminating DN is associated, and with a third node with which a peripheral DN is associated, the software further comprising logic means which is:
responsive to being advised by the second node that a first connection through the first and second nodes between the originating DN and the terminating DN cannot be established because the terminating subscriber line is busy, for providing the peripheral DN to the second node, whereby a second connection may be established through the first and third nodes between the originating DN and the peripheral DN for a telecommunications device associated with the peripheral DN to offer the originating CPE a selection between a first option of conveying the information by message to a message means associated with and accessible to a recipient at the terminating CPE and having an associated message DN, and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available;
responsive to being advised that the first option was selected, for providing the message DN to the second node and issuing a first direction to the second node to establish a third connection through the first and second nodes between the originating DN and the message DN for conveying the information by message from the originating CPE to the message means for retrieval;
responsive to being advised that the second option was selected, for issuing a second direction to monitor the terminating subscriber line and when the terminating subscriber line is no longer busy, to so advise the remote processing node; and responsive to the remote processing node being advised by the second node that the terminating subscriber line is no longer busy, for issuing a third direction to the first node to issue a request to the second node to establish a fourth connection through the first and second nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPS to the terminating CPE.

26. In a telecommunications system for conveying information across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from an originating CPE connected to the telecommunications network at a first node and having an associated originating directory number (DN), to a terminating CPE connected to the telecommunications network at a second node by a terminating subscriber line and having an associated terminating DN, responsive to a sequence of dialled digits sent from the originating CPE which denotes the terminating DN, software on a computer-readable medium for use in a telecommunications device having an associated peripheral DN, for connection with a third node with which the peripheral DN
is associated, the software further comprising logic means responsive to the establishment of a second connection, through the first and third nodes between the originating DN and the peripheral DN in the event that a first connection through the first and second nodes between the originating DN and terminating DN cannot be established because the terminating subscriber line is busy, for:
offering the originating CPE a selection between a first option of conveying the information by message to the message means associated with and accessible to a recipient at the terminating CPE and having an associated message DN and a second option of conveying the information directly to the terminating CPE when the terminating subscriber line subsequently becomes available, and providing the selected option to a remote processing node connected to the first, second and third nodes, whereby the remote processing node may, in response to the selected option, either:
direct the second node to establish a third connection through the first and second nodes between the originating DN and the message DN for conveying the information by message from the originating CPE to the message means for retrieval, or direct the second node to monitor the terminating subscriber line and when the terminating subscriber line is no longer busy, to so advise the remote processing node whereby the remote processing node may direct the establishment of a fourth connection through the first and second nodes between the originating DN and the terminating DN for conveying the information directly from the originating CPE to the terminating CPE.

27. In a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), a plurality of service switching point (SSP) nodes at the local exchanges operating with Advanced Intelligent Network (AIN) applications software and being capable of exchanging Signalling System 7 (SS7) messages with other nodes, a service control point (SCP) node adapted to exchange SS7 messages with other nodes and an intelligent peripheral (IP), a method of processing a call across the network from an originating CPE connected to a first SSP and having an associated originating directory number (DN) to a terminating CPE connected by a terminating subscriber line to a second SSP
and having an associated terminating DN, the method comprising the steps of:
the first SSP detecting a sequence of dialled digits sent from the originating CPE which denote the terminating DN, the first SSP issuing a first request that a first telecommunications link be established between the originating CPE and the terminating CPE;
the second SSP receiving the first request;
the second SSP detecting if the terminating subscriber line is busy, so that the first telecommunications link cannot be established;
if the terminating subscriber line is not busy, the first and second SSPs establishing the first telecommunications link between the originating and terminating CPEs through the first and second SSPs;
the SCP maintaining data identifying the IP, if the terminating subscriber line is busy, the second SSP
sending a first information message to the SCP that the terminating subscriber line is busy;
the SCP sending a first action request comprising the data identifying the IP to the second SSP, responsive to the first information message, requesting that the second SSP , using the data, issue a second request that a second telecommunications link be established between the IP and the originating CPE;
the second SSP issuing the second request;
a third SSP connected to the IP receiving the second request;
the first and third SSPs establishing the second telecommunications link between the IP and the originating CPE;
the IP playing an announcement to the originating CPE
across the second telecommunications link, offering a selection to the originating CPE between a first option of forwarding the call to a message means, associated with and accessible to a recipient at the terminating CPE whereby a message may be left, or a second option of terminating the call and when the terminating subscriber line subsequently becomes available, establishing a third telecommunications link between the originating and terminating CPEs;
on receipt of a second sequence of at least one dialled digit representing the selected option, the IP sending a second information message comprising the selected option to the SCP;
the SCP receiving the second information message and examining the selected option;
the SCP maintaining data identifying the message means;
if the first option was selected, the SCP sending a second action request comprising the data identifying the message means to the second SSP requesting that the second SSP, using the data, establish a fourth telecommunications link through the second SSP between the originating CPE and the message means; and if the second option was selected:
the SCP sending a third action request to the second SSP requesting that the second SSP terminate the first call, the SCP sending a fourth action request to the second SSP requesting that the second SSP monitor the busy/idle status of the terminating subscriber line, the second SSP monitoring the busy/idle status of the terminating subscriber line;
when the terminating subscriber line is no longer busy, the second SSP sending a third information message noting this status to the SCP, the SCP, responsive to the third information message, sending a fifth action request to a first node in the network requesting it to issue a third request that a third teleccmmunications link be established between the originating CPE and the terminating CPE, the first node issuing the third request, a second node receiving the third request, and the first and second nodes establishing the third teleccmmunications link between the originating and terminating CPEs through the first and second nodes.

28. The method according to claim 27, in which the first node is the first SSP and the second node is the second SSP.

29. The method according to claim 27, in which the first node is the second SSP and the second node is the first SSP.

30. The method according to claim 27, in which the first and second SSPs are the same.

31. The method according to claim 27, in which the first and third SSPs are the same.

32. The method according to claim 27, in which the second and third SSPs are the same.

33. A method of processing a call across a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), from a caller at an originating CPE to an intended recipient at a terminating CPE connected by a terminating subscriber line to a node at a local exchange and having message means associated with and accessible to the intended recipient, comprising the steps of:
the caller dialling a sequence of dialled digits at the originating CPE to request that a first call be placed across the network between the originating CPE and the terminating CPE;
the network setting up the first call between the originating CPE and the terminating CPE;
the network detecting if the terminating subscriber line is busy so that the first call cannot be completed;
if the terminating subscriber line is busy, the network playing an announcement to the caller at the originating CPE
offering a selection between the network forwarding the first call to the message means whereby a message may be left or the network terminating the first call and when the terminating subscriber line subsequently becomes available, the network setting up a second call across the network between the originating CPE and the terminating CPE;
the caller dialling a second sequence of at least one dialled digit at the originating CPE to select one of the offered selections;
on receipt of the second sequence of at least one dialled digit from the originating CPE, the network processing the second sequence and depending on the sequence, either forwarding the first call to the message means or terminating the first call, determining when the terminating subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.

34. In a telecommunications network comprising a plurality of local exchanges connected to customer premises equipment (CPE), a method of processing a caller from an originating CPE to a terminating CPE connected by a terminating subscriber line to a node at the local exchange, comprising:
setting up a first call across the network between the originating CPE and the terminating CPE, detecting if the terminating subscriber line is busy so that the first call cannot be completed, before returning a busy indication to the originating CPE, if the terminating subscriber line is busy, playing an announcement to the originating CPE offering at least a first option of terminating the first call and when the terminating subscriber line subsequently becomes available, setting up a second call across the network between the originating CPE and the terminating CPE, and on receipt of a first sequence of at least one dialled digit from the originating CPE which corresponds to the first option, determining when the terminating subscriber line is no longer busy and when the terminating subscriber line is no longer busy, setting up the second call.

35. A method according to claim 34, in which the announcement offers a second option of forwarding the first call to a voice mail box associated with and accessible to a recipient at the terminating CPE.

36. A method according claim 35, further comprising:
on receipt of a second sequence of at least one dialled digit from the originating CPE which corresponds to the second option, forwarding the first call to the voice mail box.

37. A method according to claim 34, in which the offers a third option of forwarding the first call to a forwarding CPE
connected to the network associated with and accessible to a recipient at the terminating CPE.

38. A method according to claim 37, further comprising:
on receipt of a third sequence of at least one dialled digit from the originating CPE which corresponds to the third option, forwarding the first call to the forwarding CPE.