Patent ID: 7958242
Filing Date: 2011-06-07
Classification: H04L

Abstract:
1. A method for establishing a media session comprising at least one media stream between a first terminal and a second terminal through a packet switched communications network, wherein the at least one media stream is communicated using a media transport protocol, the method comprising the following steps performed by the first terminal: transmitting a set-up message to the second terminal using a session management protocol to initiate the session, wherein the message comprises a session description suggesting a media format and corresponding parameters and attributes for each media stream to be communicated in the media session, receiving a response to the set-up message using the session management protocol, wherein the response to the set-up message comprises a amended session description, wherein the amended session description suggest an alternative media format for at least one media stream of the media session for which a media format not supported by the second terminal has been suggested in the session description comprised in the set-up message, for each alternative media format in the session description comprised in the response to the set-up message, determining if a respective alternative media format is supported by the first terminal, if not, detecting for each alternative media format not supported by the first terminal at least one NSIS router using the Next Step In Signaling (NSIS) framework, wherein a detected NSIS router is capable of converting the packet data of a media stream from the media format suggested by the first terminal in the session description in the set-up message into the respective alternative media format suggested by the second terminal in the session description of the response in the set-up message, if at least one NSIS router has been detected for each alternative media format not supported by the first terminal, reserving resources for converting packet data in the suggested media format into the respective alternative media format at least one NSIS router detected for a respective alternative media format not supported by the first terminal, and starting the media session, upon having successfully reserved the resources for media format conversion, wherein the packet data of the at least one media stream of the media session is provided using the media transport protocol from the first terminal to the second terminal through the at least one NSIS router on which resources for media format conversion have been reserved for each alternative media format not supported by the first terminal.