Nortel Networks Corporation

Genband US LLC

Noetel Networks Limited

Graeme A Gibbs

Martin Sabry

Rade Gvozdanovic

Dominic Walker

Cho Y Tang

Mark Stewart

Rade Gvodanovic

In a communications network, voice and facsimile calls are established between first and second and second terminals via first and second media gateways in a communications network. Each gateway is capable of autonomous transitioning between a voice over IP (VoIP) call mode and a facsimile over IP (FoIP) call mode. A bearer path for the call is established via a media gateway controller. During call setup, the media gateways exchange confirmation of each gateway's capability to perform autonomous transitioning between VoIP and FoIP call modes. The call is established as a VoIP call, and, on a determination by the media gateways that a facsimile call is required, each media gateway autonomously transitions between its VoIP and FoIP call modes without the intervention of the media gateway controller.

Voice and fax over IP call establishment in a communications network

A packet-based network carries a stream of voice band data, such as PCM voice data, which can include tandem free operation (TFO) information. Voice data is usually subject to processing, such as compression, at an ingress entity. The ingress entity determines whether the stream of voice data contain tandem free operation (TFO) information and, if TFO information is present, sends the TFO information across the packet network without subjecting it to processing. This preserves the integrity of the TFO information. TFO information can be carried by an unprocessed channel having a bandwidth of less than 64 kbit/s. TFO information is reinserted at an egress entity of the packet network.

Tandem free operation over packet networks

Connection admission control to an ATM network from a plurality of sources sharing a common virtual channel connection in which information packets are carried in cells is effected by determining whether that connection requires the transmission of a single packet per cell, partially filled cells containing more than one packet or fully filled cells. Where a single packet is to be transmitted per cell, the bandwidth requirement is calculated via a first algorithm. Where fully filled cells are to be transmitted, the bandwidth requirement is calculated via a second algorithm. Where partially filled cells containing more than one packet are to be transmitted the bandwidth requirement is calculated via an interpolation between the two algorithms. This provides a more accurate measure of equivalent bandwidth and thus facilitates efficient use of network resources.

Providing connection admission control in a communications network

Voice traffic is transported between first and second media gateways over a virtual channel connection incorporated in a virtual trunk group in a packet or cell based network The virtual channel connection (VCC) is agreed between the gateways via a mutual exchange of session descriptors. Typically, the VCC is selected or created by a terminating gateway, and this information is relayed in a returned session descriptor to an originating gateway so that the connection can then be established. The session descriptor may also be used to carry information whereby the gateways can negotiate an adaptation layer and/or a connection fabric to be used.

Carrying voice traffic over broad band networks

A connection admission controller determines whether to admit the requested connection according to whether admission would cause a bandwidth used to exceed a maximum bandwidth allowed. For determining the bandwidth used, an aggregate equivalent bandwidth of all connections is determined by determining a static approximation and a flow approximation, the flow approximation having a non-linear relationship to the number of connections. Using a non linear relationship enables the equivalent available capacity for a number of connections to be determined more accurately with less computational resources.

Derivation of equivalent bandwidth of an information flow

Admission control for a communications link involves maintaining a record at each end of the link of which channels on the link are free and allocating a free channel so that the probability of both ends allocating the same channel to different information flows is controllable. The record of channel identifiers is searched sequentially in different directions by the respective ends of the link to minimise the probability of simultaneous allocation before the records at each end are synchronised. New requests for admission to the link are allowed a different bandwidth threshold than requests for changes to existing connections already admitted to the link.

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Saffron Walden, United Kingdom

Graeme A Gibbs