FI105744B - Signalling in a telecommunications system - Google Patents

Description

105744

Signaling in a telecommunications system Signallering i et telekommunikationssystem

Field of the Invention r ....._ ΤΓΪ Is 5

The present invention relates to signaling in a telecommunications system and in particular to the transmission of signaling information over a packet switched network I. ~~ j f. SH®® · * · '! 10

Background of the Invention

For the transmission of speech and other user data Conventional telecommunication networks generally have upgraded to specific telecommunications network infrastructures and transmission protocols. However, with the recent explosion of digital communication, notably through the use of intranets and the Internet, the telecommunications community 20 has moved towards more general infrastructure and use of common communication protocols. The motive behind this transition is, first and foremost, the quest for interoperability between telecommunications networks and other information networks and, secondly, the cost and performance benefits offered by public telecommunications systems 25 compared to traditional telecommunications systems.

In 1996, the International Telecommunications Union (ITU) defined 30 standards for the transmission of multimedia data over local networks • · - - ..

n (Local Area Networks, LANs) as well as a number of shared LANs called "inter-networks1" ("Internetworks"), this standard is known as H.323, and the 1998 updated version is known as H.323 ver-35 as Sio 2. A fundamental and essential part of H.323 is the capability to transmit digitized and "compressed voice data • · -----— _ - * 2 105744. However, H.323 also has optional capabilities for transferring video and other data formats.

For negotiations to establish a call between two H.323 terminals, to establish a channel between them for transmitting user and signaling information, H.323 will definitely make use of ITU standard Q.931. In addition, Q.931 is mandatory for certain call maintenance and termination functions.

Known as ISDN (Integrated Services Digital Network), this is perhaps the most advanced protocol in the telecommunications network. In a connection between a subscriber and its local exchange (subscriber 15 "subscriber access point"), ISDN uses a signaling protocol known as DSS1 (Digital Subscriber Signaling System), while transmitting signaling information within a network, i.e. 20 nantes, ISDN uses another protocol known as ISUP (ISDN User Part).

In today's competitive telecommunications market, it is vital for telecoms operators to be able to offer a wide and varied range of value-added services, as well as to minimize the cost of services to end-users. As such, existing telecommunication network protocols, and especially ISDN, have evolved to allow the transmission of multiple messages and parameters associated with such services between different nodes (i.e., · signaling points) of networks.

Because signaling protocol Q.931 is largely based on DSS1, the interoperability between ISDN and H.323 is generally satisfactory. Thus, it is possible to replace the ISDN middleware with the H.323 network (or rather, the TCP / IP network using the H.323 protocol). For example, 3 105744 communication between two telephone exchanges can be made through the H.323 network. However, problems arise when interoperability between non-ISDN networks and H.323 is required.

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Summary of the present invention

The present inventors have found that Q.931 based H.323 signaling protocol 10 is unable to handle certain messages generated within a Public Switched Telephone Network (PSTN). More specifically, it has been revealed that the existing Q.931 based signaling protocol is unable to handle call "clearback" / "reanswer" messages generated at the PSTN access point of the B subscriber For B-subscriber closure and subsequent unlocking. These messages are intended to be forwarded back through the network 20 to the call billing point so that when the call billing point receives a clearback signal, a timer is triggered and the call billing end stops unless the call billing point receives reanswer signaling within a predetermined time interval.

25

The object of the present invention is to eliminate or at least alleviate the above disadvantages of the present telecommunication signaling systems. The present object of the invention is further to provide a telekommuni-30 communication systems employing packet-switched ^ network user's speech - and-conveying data information and signaling information, and wherein the clear back / reanswer-mercaptopurine, "signaling between can be transferred to the called party liityntäpis ment which lays call laskutuspisteelle call billing 35 to stop or delay the cumulative action.

According to a first aspect of the present invention, a method for transmitting a call clearback and / or reanswer message from a PSTN access point to a call billing point over a packet switched network using the Q.931 signaling protocol is disclosed, method 5 comprising a call clearback and reanswer parameter. including one or another parameter as a Notification Indicator message element in the NOTIFY message in the Q.931 protocol, to be transmitted over 10 packet switched networks in response to the generation of a clearback or reanswer message at the PSTN access point.

The current Q.931 standard defines a data element Noti-15 fication Indicator, which forms part of the NOTIFY message, which has a number of reserved (i.e., unused) states. The present invention utilizes these reserved states to transmit clearback / reanswer parameters.

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Preferably, the extended Q.931 protocol used by the present invention is provided for application in the H.323 protocol stack. Even more preferably, said connection or part of the connection between the subscriber parties is established over a TCP / IP-25 based network. This network may be a LAN, an in-ter network, the Internet, or a combination of two or more. In these cases, the H.323 protocol stack is created above the TCP / IP protocol stack.

Preferably, the method consists of polling for a B subscriber B from said PSTN access point to detect phone closure and phone opening and generating either a clearback message or a reanswer message at 35 PSTN access points in response to such detection.

According to another aspect of the present invention, there are provided 5,105,744 apparatus for transmitting a call clearback and / or reanswer message from a PSTN access point to a call counting point over a packet switched network using the Q.931 signaling protocol, the apparatus consisting of 5 PSTN access points and a packet , the function of which is to include one or other of the defined call clearback and re-answer parameters as a Q_! _ 931 based NOTIFY message Notification Indicator data element in response to the I10 call clearback or ^^ reariswer message generation at the PSTN access point, and_J ^ send a NOTIFY message over the packet switched data network at the call billing point I '! tea.

i · · · ·; '.niKnvss: - 15 Description of the Drawings lvhvt

In order to better understand the present invention and to see how it may be implemented, reference will now be made by way of example to the accompanying drawings, in which: Figure 1 is a schematic diagram of a telecommunications network in which user information and signaling information is transmitted between network exchanges; and

Figure 2 is a flowchart illustrating the transmission of telephone closure and unlock signaling information in the network of Figure 1.

Detailed Description of Certain Embodiments

The following description is based on the presentations of ITU Standard H.323, where the use of a Q. 931 based standard to establish and maintain a call connection between two ··· 323-capable terminals is made mandatory. In the example shown in Fig. 1, two telecommunication network exchanges 1,2 have means for H.323 communication 35 for processing signaling and transmitting it respectively. H.323 protocol stacks are located in the TCP / IP protocol stack. over layers so that H.323 data can be transmitted between 6 105744 exchanges via IP network 3.

The exchanges 1.2 have 4.5 PSTN access points (i.e., non-ISDN) for the respective subscriber terminals in the telecommunications network.

5 For purposes of the present example, it is assumed that terminals 4.5 are connected to corresponding PSTNs via Plain Old Telephone Service (POTS) networks only. In the case of a call between two terminals 4.5, the terminal 4, 10 from which the call is made is referred to as the calling party, while the other terminal 5 is referred to as the answering party. It should be noted that switches 1,2 may be located in a single operator network or may be in networks of different operators. It is also to be noted that terminals 4,5 may be connected to respective access centers 1,2 via intermediate routing nodes.

Central 1 is the caller party terminal 4 initiated by a call 20 collector of information affecting the billing provisions. Specifically, the center 1 transmits information such as call start and lopetusmerkinannot and the caller party and the answering party's location the call record-system 6 that calculates the puhelutietuetiedot a particular call based on the center of the information received from one and 25 certain tariff predetermined (including subscriber-specific tariff) priming below.

Q.931 defines a NOTIFY message having the following 30 structure, where the Reference indicates a ···. in the Q. 931 standard, the Direction indicates which direction (s) the data element may carry with the NOTIFY message (n = network, u = H.323 user), and the Length (Length) ) 35 indicates element length in octets: m 7 105744

Data Element Reference Direction Type Length __ (Sub-clause) ___ 5 Protocol- 4.2 Both M 1 Separator_____

Call Reference 4.3 Both M 2

Message Type 4.4 Both M 1 10 ----- i Network 4.5 n-> u O 2-12 | of service

Notification Indicator 4.5 Both M 3 15 Coders Display 4.5 n -> u O> 2 20 One of the six message elements is the Notifier Indicator, for which the existing standard Q.931 defines three meaning values, which are:

Bits 25 7654321 • 0000000 User suspended 0000001 User resumed 0000010 Bearer service change 30 ** All other modes are currently reserved.

• · ''. .

Disclosed herein is a proposal for a "oh Q.931 protocol extend two lisäsänoman (parameter) corresponding to 35 to provide a voice detection party (subscriber B ^ ''), opening the phone and the phone is closed. For these two messages, two arbitrary Noti-

Claims (7)

105744 The reserved space for the fication Indicator element. For example, suppose a call is in progress between terminals 1,2 and the answering party terminates the call by closing the telephone (B-initiated call termination, A method for transmitting a call clearback and / or reanswer message 105744 from a PSTN access point to a call billing point via a packet switched network using a signaling protocol based on Q.931, characterized in that the method comprises a call clearback and a reanswer * 5. specifying parameters and including one of the parameters as a Notification Information element in a Q.931 protocol NOTIFY message for transmission over a packet switched network in response to call clearback or reanswer message generation at the 10 PSTN access points. Method according to claim 1, characterized in that the extended Q.931 protocol is arranged to be applied in the H.323 protocol stack. 15 A method according to claim 2, characterized in that said connection or part of the connection between the subscriber parties is established over a TCP / IP network. Method according to claim 3, characterized in that the H.323 protocol stack is provided on top of the TCP / IP protocol stack. 5. In any one of the preceding claims 25, characterized "on" and Notification Indicator - the data element is available to be transferred to answering party access point 'billing center or soit-tajaosapuolen to the access point in response to the answering party phone avaamistoiminnolle, an element conveying - * · 30 respectively phone avaamisilmoitusta value. . 5 B-Subscriber Initiated Call Clearing, B-ICC). To terminate the billing operation, the Toll Ticketing System 6 must receive a Call Clear Request (CCR). Located two polls the answering party terminal 10 for detecting the four phone close operation, and generates the result of finding the "clear back '' - signaling center 2 generates then a NOTIFY message with Notification Indicator element has a clear back message to a corresponding value, and further transfers this message to the IP. 1. If the B-subscriber re-opens his / her telephone within a predetermined period of time (e.g., 90 seconds), the exchange 2 will detect this and call "reanswer" message will be generated. 2 generates a NOTIFY message having a value corresponding to the reanswer message as a Notification Indicator element, which is then passed to the initiating exchange 1 over IP network 3. 25 Figure 2 is a flowchart showing a call between two terminals 4.5 and during a call responsible-jaosapuolen relating to an action 5 of cessation It will be apparent to one skilled in the art that various modifications may be made to the embodiment described above without departing from the scope of the present invention. 35 Claims 6. The method of any one of ..edellisen claims, characterized in that the method comprises the executable corresponding to the j aosapuolen access point voice mail polling with 35 sides. phone lock function ·. ' to detect. 105744 Apparatus for transmitting a call clearback and / or reanswer message from a PSTN access point to a call billing point over a packet switched network using the Q.931 signaling protocol, characterized in that the apparatus comprises a PSTN access point and a packet switched node defined call clearback and reanswer parameters as a data element of one of the 10.9 NOTIFY message Notification Indicator based on the Q.931 based protocol in response to generating a call clearback or reanswer message at the PSTN access point and transmitting the NOTIFY message via packet switched call point. 15