Method and apparatus for communication in communication system supporting multi-talker mission critical push-to-talk (mcptt)

A device including a mission critical push-to-talk (MCPTT) client in a communication system, the device comprising:

• a transceiver;
• one or more processors including processing circuitry;
• and
• memory storing instructions that, when executed by the one or more processors individually or collectively, cause the MCPTT client to:
• in response to the MCPTT client initiating a call with an implicit floor request, transmit to a MCPTT server via the transceiver, a session description protocol (SDP) offer including a first synchronization source (SSRC) value as a media attribute of a SDP and the implicit floor request as a format specific parameter (fmtp) attribute, and
• receive, via the transceiver from the MCPTT server, a SDP answer, based on the SDP offer,
• wherein the SDP answer includes either the first SSRC value or a second SSRC value in response to whether or not the first SSRC value in the SDP offer is being used.

A method performed by a mission critical push-to-talk (MCPTT) server in a communication system, the method comprising:

• receiving, from a MCPTT client, a session description protocol (SDP) offer;
• identifying that the SDP offer includes a first synchronization source (SSRC) value as a media attribute of a SDP and an implicit floor request as a format specific parameter (fmtp) attribute;
• transmitting, to the MCPTT client, a SDP answer including the first SSRC value in response to the first SSRC value in the SDP offer not being used;
• and
• transmitting, to the MCPTT client, a SDP answer including a second SSRC value in response to the first SSRC value in the SDP offer being used.

A mission critical push-to-talk MCPTT server in a communication system, the MCPTT server comprising:

• a transceiver;
• and
• one or more processors including processing circuitry;
• and
• memory storing instructions that, when executed by the one or more processors individually or collectively, cause the MCPTT server to:
• receive, via the transceiver from a MCPTT client, a session description protocol SDP offer,
• identify that the SDP offer includes a first synchronization source (SSRC) value as a media attribute of a SDP and an implicit floor request as a format specific parameter (fmtp) attribute;
• transmit, to the MCPTT client via the transceiver, a SDP answer including the first SSRC value in response to the first SSRC value in the SDP offer not being used;
• and
• transmit, to the MCPTT client via the transceiver, a SDP answer including a second SSRC value in response to the first SSRC value in the SDP offer being used.