Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Patent
1998-11-12
2000-10-03
Tsang, Fan
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
455560, 455414, H04Q 720
Patent
active
061284955
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to the provision of intelligent network (IN) services to subscribers of a mobile communications system.
BACKGROUND OF THE INVENTION
Wireless communications systems for mobile subscribers, such as the Global System for Mobile Communications (GSM) cellular system, are well established. In fixed networks it is known to provide subscribers with special services such as Freephone, call forwarding and call barring. These call control services are provided by an intelligent network (IN) which forms an additional layer of the network. By separating some of the call control functions from network switches, services can be developed and applied independently. An intelligent network comprises a number of Service Switching Points (SSPs) which are linked to Service Control Points (SCPs). The SSPs are programmed to recognise `trigger` events, such as a particular pattern of digits (e.g. 0800 for Freephone), and to refer any calls in which a trigger occurs to the SCPs to apply the required service.
It is now intended to provide IN services to mobile subscribers, which requires physical linking of the Public Land Mobile Network (PLMN) to an IN, and establishing protocols to ensure that calls requiring IN services are correctly routed.
Some known arrangements for providing intelligent network services to subscribers of a mobile network are shown in U.S. Pat. No. 5,345,502 (Rothenhofer) and European Patent Application EP 0 630 165 A2 (Alcatel).
International Patent Application WO 95/26114 relates to an intelligent mobile telecommunications network with communication between a logical node of an intelligent network and a logical node of a mobile network.
International Patent Application WO 93/18606 describes an Advanced Intelligent Network (AIN) wireline system which connects to and controls processing of calls to a Personal Communications Service subscriber's wireless handset.
There have been some problems with routing calls between mobile and intelligent networks, which has resulted in calls being incorrectly completed. There is a particular problem where the application of an IN service on the terminating leg of a call requires a call to be completed to the originally called party. The mobile network may repeatedly route the same call to the IN in an infinite loop.
It is an object of the present invention to minimise or overcome these routing problems for calls requiring intelligent network (IN) services.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of routing calls which require intelligent network (IN) services between a pair of subscribers, at least one of which subscribers is a mobile network subscriber, the method including routing a call from a mobile network to an intelligent network via a first path to apply an IN service, and routing the call back to the mobile network via a second path or a third path, wherein calls routed via the second path are completed to the called party without further routing to the IN, and wherein for calls routed via the third path the mobile network determines whether a further routing of the calls to the IN is required prior to completion.
This provides a mechanism for enabling the mobile network to differentiate calls which do not require further routing to the IN. Thus infinite routing loops can be avoided. It is achieved in a manner which can avoid changes to the signalling between the IN and mobile networks.
Preferably each path is a separate trunk or a group of trunk lines.
Preferably calls are routed via the third path if the intelligent network determines that, as a result of applying a terminating IN service, a new called party is involved. This enables calls to be routed to an IN for services to which the new called party subscribes.
Calls are routed via the third path if the intelligent network applies an originating IN service for a calling party and where subsequent routing to the IN may be required to apply a terminating IN service. This enables calls to be routed back to an IN where r
REFERENCES:
patent: 5345502 (1994-09-01), Rothenhofer
patent: 5469496 (1995-11-01), Emery et al.
patent: 5673308 (1997-09-01), Akhavan
patent: 5920816 (1999-07-01), Khan et al.
patent: 5926760 (1999-07-01), Khan et al.
Clapp Bradford
Sharp Iain
Welling James B
Nortel Networks Corporation
Perez-Gutierrez Rafael
Tsang Fan
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