Nortel Networks Corporation

Cuthbert Cheung

Peter Tarle

David Ward

Erl&eacute; De Pillot

Ian Astle

Sandrine Millet

Ian D Sinclair

Percy Lau

Michel Thibon

John Marshall

Gwen Clarke

Aline Gateau

A system and method for routing calls from a time-division multiplexed (TDM) sets in an IP network to a geographically appropriate portion of the public switched telephone network (PSTN). A call is routed to an edge gateway in a geographic location corresponding to the geographic location of an IP media gateway to which the TDM set is connected. Each IP media gateway is associated with a geographic zone. Each geographic zone is also associated with at least one edge gateway. Accordingly, incoming calls are routed by the central call server based upon the geographic zone associated with the IP media gateway receiving the call, and are routed to an edge gateway associated with the identified geographic zone. The system and method may be applied to route emergency service access calls to an appropriate portion of the PSTN so that they arrive at a geographically appropriate public service answering point (PSAP).

Localization of call routing for TDM sets in an IP network

A quality of service (QOS) server gathers information in relation to transport introduced delays and obliterations of so called real-time protocol (RTP) signal streams which are used to packetize signals of synchronous signals origins, for example origins such as telephones and raster scan apparatus, for transport via the IP network. The QOS server is able to provide recently gathered QOS information about a requested call, apriori the actual call set up. In an example of a PBX call centre, an automatic dialler is coupled with a QOS server and in relation to endpoint and route selected data, determines if an IP telephony call should proceed, contingent upon the probable QOS being sufficient, before a call controller initiates a call set up.

Internet protocol (IP) telecommunication

Methods and apparatus are described for maintaining established local calls at an access module in case of change of the call control for a distributed PBX over a communications network, e.g. WAN or LAN, especially an IP network. In accordance with a first main embodiment, the system is composed of one Call Server controlling the call processing of other PBX access modules in a normal situation. These access modules have the ability to operate in Stand Alone or Survival mode if the link to the Call Server is down for any reason. In a second main embodiment, two call servers may be used, an active call server and a hot-standby server. The active call server controls the call processing of the access modules. In case the link between one access module and the active call server fails, the hot-standby Call Server can take over the control of the access module. Therefore, each module can operate in normal mode of the active call server or in normal mode of the hot-standby call server or, as an alternative to either of these, in stand alone or survival mode.

Network based distributed PBX with connection loss survival features

Growing community of inventors

Belleville, Canada

Cuthbert Cheung