A method of setting up a communication session based upon Session Initiation Protocol, SIP, comprising: sending (700; 800A; 1000A; 1000B; 1000C; 1100A; 1100B) an invite to the communication session to multiple target devices (200; 400) from an originating device (200; 400); receiving (705; 810A; 1105A; 1105B) a first packet of a first media stream from a first target device of the multiple target devices prior to receipt of a signaling indication that any of the multiple target devices accepts the invite; receiving (710; 800B; 1015A; 1015B; 1110A; 1110B), after the reception of the first packet of the first media stream and prior to receipt of the signaling indication, a first packet of a second media stream from a second target device of the multiple target devices; selecting (710; 805B, 810B, 815B, 820B; 1010A, 1015A; 1010B, 1015B; 1010C, 1015C; 1115A; 1115B) between the first and second media streams for the communication session based at least in part upon (i) a source identifier contained in the first packet of the first media stream and/or the first packet of the second media stream in a manner that is independent of any signaling information received in association with setup of the communication session, or (ii) signaling information that indicates a forking context for the communication session and is received prior to the signaling indication that any of the multiple target devices accepts the invite, the forking context indicating a manner in which one or more proxies redirect data in conjunction with setup of the communication session; loading (710; 825B; 1020A; 1020B; 1115A; 1115B) a codec associated with playback of the selected media stream; and playing (720, 735; 825B; 1025A; 1025B; 1115A; 1115B) the selected media stream prior to receipt of the signaling indication sending (700; 800A; 1000A; 1000B; 1000C; 1100A; 1100B) an invite to the communication session to multiple target devices (200; 400) from an originating device (200; 400); receiving (705; 810A; 1105A; 1105B) a first packet of a first media stream from a first target device of the multiple target devices prior to receipt of a signaling indication that any of the multiple target devices accepts the invite; receiving (710; 800B; 1015A; 1015B; 1110A; 1110B), after the reception of the first packet of the first media stream and prior to receipt of the signaling indication, a first packet of a second media stream from a second target device of the multiple target devices; selecting (710; 805B, 810B, 815B, 820B; 1010A, 1015A; 1010B, 1015B; 1010C, 1015C; 1115A; 1115B) between the first and second media streams for the communication session based at least in part upon (i) a source identifier contained in the first packet of the first media stream and/or the first packet of the second media stream in a manner that is independent of any signaling information received in association with setup of the communication session, or (ii) signaling information that indicates a forking context for the communication session and is received prior to the signaling indication that any of the multiple target devices accepts the invite, the forking context indicating a manner in which one or more proxies redirect data in conjunction with setup of the communication session; loading (710; 825B; 1020A; 1020B; 1115A; 1115B) a codec associated with playback of the selected media stream; and playing (720, 735; 825B; 1025A; 1025B; 1115A; 1115B) the selected media stream prior to receipt of the signaling indication