EP1131957A1 - Signalling in a telecommunications system - Google Patents
Signalling in a telecommunications systemInfo
- Publication number
- EP1131957A1 EP1131957A1 EP99963302A EP99963302A EP1131957A1 EP 1131957 A1 EP1131957 A1 EP 1131957A1 EP 99963302 A EP99963302 A EP 99963302A EP 99963302 A EP99963302 A EP 99963302A EP 1131957 A1 EP1131957 A1 EP 1131957A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- network
- signalling
- protocol
- data
- isup
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q3/00—Selecting arrangements
- H04Q3/0016—Arrangements providing connection between exchanges
- H04Q3/0025—Provisions for signalling
Definitions
- the present invention relates to signalling in a telecommunications system and more particularly to the transmission of signalling data over a packet switched network .
- H.323 the International Telecommunications Union
- H.323 Version 2 A fundamental and essential component of H.323 is the provision for the transmission of digitised and compressed voice data.
- H.323 also makes optional provision for the transmission of video and other data forms .
- H.323 makes mandatory the use of the ITU standard Q.931 for the negotiation of a call set-up between two H.323 terminals, to establish a channel therebetween over which the terminals may send user and signalling data.
- Q.931 is mandatory for certain call maintenance and termination functions.
- ISDN International Standard Digital Network
- DSS1 Digital Subscriber Signalling System No.l
- ISUP ISDN User Part
- PSTN Public Switched Telephone Network
- the inventors of the present invention have discovered that the existing Q.931 based signalling protocol employed by H.323 is not able to accommodate certain messages generated within an ISUP based ..network. More particularly, it has been discovered that the existing Q.931 based signalling protocol is unable to accommodate the Network Discard Indicator message which may be generated at a switch of a telecommunication network in the event that the switch does not support User-to-User signalling information contained in a received Q.931 message.
- This deficiency in the Q.931 based signalling protocol means that there is no way in which the switch, from which the User-to-User signalling information originated, can be informed for example that the receiving switch has discarded the signalling information. In certain circumstances this may lead to overcharging of the calling party.
- a method of communicating signalling data between a pair of telecommunication switches employing ISUP signalling, via a packet switched data network comprising using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of the ISUP Network Discard Indicator message.
- the extended Q.931 protocol employed by the present invention is arranged to be applied within an H.323 protocol stack. More preferably, said connection or part of a connection formed ..between the subscriber parties is provided over a TCP/IP based network.
- This network may be a LAN, an internetwork, the Internet, or a combination of two or more of these.
- the H.323 protocol stack is provided over a TCP/IP protocol stack.
- apparatus for communicating signalling data between a pair of telecommunication network switches employing ISUP signalling, via a packet switched data network comprising means for using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of Network Discard Indicator messages.
- Figure 1 illustrates schematically a telecommunications network in which user and signalling data is carried between exchanges of the network via an IP network
- Figure 2 is a flow diagram illustrating the transmission of Network Discard Indicator messages in the network of Figure 1.
- a first telephone exchange 1 is coupled to a subscriber terminal 2 via an ISDN access network (i.e. which uses the DSS1 signalling protocol)
- a second exchange 3 is coupled to a subscriber terminal 4 via a PSTN access network.
- Interexchange signalling within the network is carried using ISUP protocol messages requiring the provision at the PSTN exchange 3 of a PSTN/ISUP interface 5.
- the terminal 2 from which the call is established is referred to as the "calling party " whilst the other terminal 4 is referred to as the "called party' * .
- the terminals 2,4 may be connected to respective access exchanges 1,2 via intermediate routing nodes (e.g. multiplexers/demultiplexers) .
- the following description builds upon the disclosures of the ITU H.323 standard which makes mandatory the use of a Q.931 based standard for establishing and maintaining a call connection between two H.323 enabled terminals.
- the two exchanges 1,3 of the telecommunications network communicate via respective H.323 enabled terminals 6,7 which in turn communicate with each other over an IP based network 8.
- the H.323 protocol stacks lie on top of TCP/IP protocol layers such that the H.323 data may be conveyed between the exchanges over the IP network 8.
- a protocol stack consisting of ISUP over Q.931 over TCP/IP.
- the calling party 2 wishes to send certain User-to-User signalling information to the called party 4 during the call set-up procedure and which is facilitated by the ISDN access network available to the calling party 2.
- This information may include, for example, call forwarding information, call waiting information, or the like.
- the information is encapsulated at the access exchange 1,6 in an appropriate Q.931 message and is sent over the H.323 network 8 to the terminating exchange 3,5,7.
- the terminating exchange 3 is incapable of making use of the received User-to-User signalling information.
- the terminating exchange 3 must generate a Network Discard Indicator message, encapsulate it within a Q.931 message, and transmit the resulting Q.931 message back to the originating exchange over the IP network
- the Notification Indicator element is defined in the existing Q.931 standard as having three meaningful values or states . These are : Bits
- Figure 2 is a flow chart illustrating the steps involved in relaying a Network Discard Indicator message from the PSTN exchange 3 to the ISDN exchange 1.
- the exchanges (or switches) between which the Network Discard Indicator message is sent may be coupled via one or more intermediate switches, with the IP network extending only over an intermediate portion of the signalling connection, e.g. between two intermediate exchanges.
- the Network Discard Indicator message may be generated either at the terminating or originating exchange, or at one of the intermediate exchanges .
- the Network Discard Indicator message may be placed directly onto the IP network by the exchange at which the message is generated, or it may first be transmitted to an intermediate exchange over, for example, a Signalling System No.7 (SS7) signalling network.
- SS7 Signalling System No.7
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Telephonic Communication Services (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
Abstract
A method of communicating signalling data between a pair of telecommunication exchanges (1,3) employing ISUP signalling, via a packet switched data network. The method comprising using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of the ISUP Network Discard Indicator message.
Description
Signalling in a Telecommunications System
Field of the. Invention
The present invention relates to signalling in a telecommunications system and more particularly to the transmission of signalling data over a packet switched network .
Bac gr un to h Invention
Conventional telecommunications networks for conveying voice and other user information have in general relied upon dedicated telecommunications network infrastructure and transmission protocols. However, with the recent explosive growth in digital data transmission, driven in particular by the use of intranets and the Internee, there has been a move towards the use of more generic infrastructure and transmission protocols in the telecommunications industry. This move is driven primarily by the desire for interoperability between telecommunications networks and other data networks, and secondarily by the cost and performance advantages which general data network systems offer over conventional telecommunications systems.
In 1996, the International Telecommunications Union (ITU) defined a standard for the transmission of multimedia data over Local Area Networks (LANs) as well as "internetworks" composed of multiple interconnected LANs. This standard is known as H.323, whilst the 1998 revision is known as H.323 Version 2. A fundamental and essential component of H.323 is the provision for the transmission of digitised and compressed voice data. However, H.323 also makes optional provision for the transmission of video and other data forms .
H.323 makes mandatory the use of the ITU standard Q.931 for the negotiation of a call set-up between two H.323 terminals, to establish a channel therebetween over which the terminals may send user and signalling data. In addition, Q.931 is mandatory for certain call maintenance and termination functions.
Perhaps the most advanced telecommunications network protocol is that known as International Standard Digital Network (ISDN) . In the link between a subscriber and that subscriber's local exchange (the subscriber "access point"), ISDN uses a signalling protocol known as Digital Subscriber Signalling System No.l (DSS1) , whilst a further protocol known as ISDN User Part (ISUP) is used to convey signalling data within the network, i.e. inter-exchange signalling. ISUP is also used more generally in inter-exchange signalling even in networks which do not make use of an ISDN access network, e.g. where the access network is a Public Switched Telephone Network (PSTN)
In the current competitive telecommunications marker, it is vital for a telecom operator to provide a wide and varied range of value added services, as well as co minimise the cost of services to the end users. As such, existing telecommunications network protocols, and in particular ISUP, have evolved to provide for the transfer of many messages and parameters relating co such services between the various nodes (or signalling points) of the networks.
As the Q.931 signalling protocol is largely based upon the DSS1 protocol, interworking between ISUP and H.323 is generally satisfactory. It is therefore possible to replace intermediate portions of an ISUP network with an H.323 network (or rather a TCP/IP network which uses the H.323 protocol) . For example, the connection between two telephone switches, e.g. exchanges, could be made via an H.323 network.
Summary of the Present Invention
The inventors of the present invention have discovered that the existing Q.931 based signalling protocol employed by H.323 is not able to accommodate certain messages generated within an ISUP based ..network. More particularly, it has been discovered that the existing Q.931 based signalling protocol is unable to accommodate the Network Discard Indicator message which may be generated at a switch of a telecommunication network in the event that the switch does not support User-to-User signalling information contained in a received Q.931 message. This deficiency in the Q.931 based signalling protocol means that there is no way in which the switch, from which the User-to-User signalling information originated, can be informed for example that the receiving switch has discarded the signalling information. In certain circumstances this may lead to overcharging of the calling party.
It is an object of the present invention to overcome or at least mitigate the above noted disadvantages of existing telecommunication signalling systems. It is a further object of the present invention to provide a telecommunications system in which a packet switched network is used to carry user voice and data information and signalling data and in which a Network Discard Indicator message may be transmitted over the network between a pair of switches .
According to a first aspect of the present invention there is provided a method of communicating signalling data between a pair of telecommunication switches employing ISUP signalling, via a packet switched data network, the method comprising using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based
protocol extended to provide for the transmission of the ISUP Network Discard Indicator message.
Preferably, the extended Q.931 protocol employed by the present invention is arranged to be applied within an H.323 protocol stack. More preferably, said connection or part of a connection formed ..between the subscriber parties is provided over a TCP/IP based network. This network may be a LAN, an internetwork, the Internet, or a combination of two or more of these. In these cases, the H.323 protocol stack is provided over a TCP/IP protocol stack.
According to a second aspect of the present invention there is provided apparatus for communicating signalling data between a pair of telecommunication network switches employing ISUP signalling, via a packet switched data network, the apparatus comprising means for using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of Network Discard Indicator messages.
Bri f np.qr i pti on of the Drawings
For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings, in which:
Figure 1 illustrates schematically a telecommunications network in which user and signalling data is carried between exchanges of the network via an IP network; and
Figure 2 is a flow diagram illustrating the transmission of Network Discard Indicator messages in the network of Figure 1.
Detailed npπr-H nti on of Certain Fmbodi ments
In the telecommunications network of Figure 1, a first telephone exchange 1 is coupled to a subscriber terminal 2 via an ISDN access network (i.e. which uses the DSS1 signalling protocol) , whilst a second exchange 3 is coupled to a subscriber terminal 4 via a PSTN access network. Interexchange signalling within the network is carried using ISUP protocol messages requiring the provision at the PSTN exchange 3 of a PSTN/ISUP interface 5. In the case of a call between the two subscriber terminals 2,4, the terminal 2 from which the call is established is referred to as the "calling party" whilst the other terminal 4 is referred to as the "called party'*. It will also be appreciated that the terminals 2,4 may be connected to respective access exchanges 1,2 via intermediate routing nodes (e.g. multiplexers/demultiplexers) .
The following description builds upon the disclosures of the ITU H.323 standard which makes mandatory the use of a Q.931 based standard for establishing and maintaining a call connection between two H.323 enabled terminals. In the example illustrated in Figure 1, the two exchanges 1,3 of the telecommunications network communicate via respective H.323 enabled terminals 6,7 which in turn communicate with each other over an IP based network 8. At the H.323 terminals 6,7, the H.323 protocol stacks lie on top of TCP/IP protocol layers such that the H.323 data may be conveyed between the exchanges over the IP network 8. Thus, at each exchange there exists a protocol stack consisting of ISUP over Q.931 over TCP/IP.
Consider the situation where the calling party 2 wishes to send certain User-to-User signalling information to the called party 4 during the call set-up procedure and which is facilitated by the ISDN access network available to the calling party 2. This information may include, for example, call forwarding information, call waiting information, or
the like. The information is encapsulated at the access exchange 1,6 in an appropriate Q.931 message and is sent over the H.323 network 8 to the terminating exchange 3,5,7. Now assume that the terminating exchange 3 is incapable of making use of the received User-to-User signalling information. In this case the terminating exchange 3 must generate a Network Discard Indicator message, encapsulate it within a Q.931 message, and transmit the resulting Q.931 message back to the originating exchange over the IP network
The Q.931 standard defines a NOTIFY message having the following structure, where the Reference indicates the corresponding Information element reference in the Q.931 standard, Direction indicates the directio (s) in which an element may be carried by the NOTIFY message (n = network, u = H.323 user) , and Length indicates the length of the element in octets :
Of the six message elements, the Notification Indicator element is defined in the existing Q.931 standard as having three meaningful values or states . These are :
Bits
7 6 5 4 3 2 1
0 0 0 0 0 0 0 User suspended
0 0 0 0 0 0 1 User resumed
0 0 0 0 0 1 0 Bearer service change
All other values are currently reserved.
What is proposed here is an extension to the Q.931 protocol to provide for the Network Discard Indicator message. This message is assigned to any one of the reserved values of the Notification Indicator element.
Figure 2 is a flow chart illustrating the steps involved in relaying a Network Discard Indicator message from the PSTN exchange 3 to the ISDN exchange 1.
It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiment without departing from the scope of the present invention. For example, whilst the above embodiment describes the inclusion of the Network Discard Indicator message in the Q.931 NOTIFY message, other messages may be used for which there currently exists reserved values. The exchanges (or switches) between which the Network Discard Indicator message is sent may be coupled via one or more intermediate switches, with the IP network extending only over an intermediate portion of the signalling connection, e.g. between two intermediate exchanges. In such a case, the Network Discard Indicator message may be generated either at the terminating or originating exchange, or at one of the intermediate exchanges . The Network Discard Indicator message may be placed directly onto the IP network by the exchange at which the message is generated, or it may first be transmitted to an intermediate exchange over, for example, a Signalling System No.7 (SS7) signalling network.
Claims
1. A method of communicating signalling data between a pair of telecommunication switches employing ISUP signalling, via a packet switched data network, the method comprising using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of the ISUP Network Discard Indicator message.
2. A method according to claim 1, wherein the extended Q.931 protocol is arranged to be applied within an H.323 protocol stack.
3. A method according to claim 2, wherein said connection or part of a connection formed between the subscriber parties is provided over a TCP/IP network.
4. A method according to claim 3, wherein the H.323 protocol stack is provided over a TCP/IP protocol stack.
5. Apparatus for communicating signalling data between a pair of telecommunication network switches employing ISUP signalling, via a packet switched data network, the apparatus comprising means for using H.323 protocol to communicate over the data network where signalling data is carried by a Q.931 based protocol extended to provide for the transmission of Network Discard Indicator messages .
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI982472 | 1998-11-16 | ||
FI982472A FI106595B (en) | 1998-11-16 | 1998-11-16 | Signaling in a telecommunications system |
PCT/EP1999/008783 WO2000030370A1 (en) | 1998-11-16 | 1999-11-15 | Signalling in a telecommunications system |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1131957A1 true EP1131957A1 (en) | 2001-09-12 |
Family
ID=8552918
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99963302A Withdrawn EP1131957A1 (en) | 1998-11-16 | 1999-11-15 | Signalling in a telecommunications system |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1131957A1 (en) |
JP (1) | JP2002530952A (en) |
CN (1) | CN1326643A (en) |
AU (1) | AU1966000A (en) |
FI (1) | FI106595B (en) |
WO (1) | WO2000030370A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4909499B2 (en) * | 2004-03-11 | 2012-04-04 | Necインフロンティア株式会社 | Message communication system |
CN100542196C (en) * | 2005-11-22 | 2009-09-16 | 华为技术有限公司 | The method and system that a kind of toll operator of realization inserts |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5550906A (en) * | 1994-08-05 | 1996-08-27 | Lucent Technologies Inc. | Telecommunications feature server |
CA2217838C (en) * | 1996-11-07 | 2003-07-29 | At&T Corp. | Wan-based voice gateway |
-
1998
- 1998-11-16 FI FI982472A patent/FI106595B/en not_active IP Right Cessation
-
1999
- 1999-11-15 WO PCT/EP1999/008783 patent/WO2000030370A1/en not_active Application Discontinuation
- 1999-11-15 AU AU19660/00A patent/AU1966000A/en not_active Abandoned
- 1999-11-15 CN CN 99813418 patent/CN1326643A/en active Pending
- 1999-11-15 EP EP99963302A patent/EP1131957A1/en not_active Withdrawn
- 1999-11-15 JP JP2000583265A patent/JP2002530952A/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO0030370A1 * |
Also Published As
Publication number | Publication date |
---|---|
FI982472A (en) | 2000-05-17 |
FI106595B (en) | 2001-02-28 |
JP2002530952A (en) | 2002-09-17 |
AU1966000A (en) | 2000-06-05 |
WO2000030370A1 (en) | 2000-05-25 |
CN1326643A (en) | 2001-12-12 |
FI982472A0 (en) | 1998-11-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5912887A (en) | System and method for implementing user-to-user data transfer services | |
US6064653A (en) | Internetwork gateway to gateway alternative communication | |
US6937596B2 (en) | IP based telephone system | |
US20020080801A1 (en) | Transmission system using packet switched network | |
US7460520B2 (en) | Apparatus and method for using multiple call controllers of voice-band calls | |
US6021136A (en) | Telecommunication network that reduces tandeming of compressed voice packets | |
RU2183913C2 (en) | Broadband telecommunication system | |
US6937612B1 (en) | Communications method and apparatus | |
EP1723770B1 (en) | Method for establishing a call in a telecommunications network; telecommunications network; and controlling device for packet networks | |
US6570868B1 (en) | System and method for establishing a communication connection | |
EP0711052B1 (en) | Improvements in or relating to telecommunication systems | |
EP1188324B1 (en) | Integration of narrowband and broadband ss7 protocol stacks | |
EP1198945B1 (en) | An ip based telephone system | |
WO2000030370A1 (en) | Signalling in a telecommunications system | |
US7436851B1 (en) | Destination call routing apparatus and method | |
WO2000070884A1 (en) | Signalling in a telecommunications network | |
EP1091552A2 (en) | Method and apparatus for providing telephone service using TDM switches and data transport networks | |
US7006493B1 (en) | Virtual voice port configured to connect a switched voice call to a permanent voice call | |
US6427007B1 (en) | System and method for completing a call while at least one call is established using analog interface to telephone network | |
FI105745B (en) | Signalling in a telecommunication system | |
WO1999049636A1 (en) | Communications network | |
GB2254520A (en) | Telecommunications signalling enhancement | |
GB2350254A (en) | Signalling in a telecommunications network | |
KR20000040818A (en) | Method for diverting receipt terminal by network switch connected to receipt terminal in atm public network | |
JPS63311836A (en) | Path setting control system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20010607 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
18W | Application withdrawn |
Effective date: 20030611 |