Method for performing multiple authentications within service registration procedure

A method performed by a session initiation protocol (SIP) core, the method comprising:

• receiving, from a user equipment (UE), a register request message;
• transmitting, to the UE, an authentication challenge message;
• receiving, from the UE, a first register message including an access token to authenticate the UE in the SIP core;
• and
• transmitting, to a mission critical push to talk (MCPTT) server, a second register message including the access token and an IP multimedia public identity (IMPU) that is to be used to validate the access token and bind the IMPU and an MCPTT identifier (ID) in case that a successful SIP authentication is performed based on the first register message.

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

• receiving a register message transmitted from a session initiation protocol (SIP) core in case that a successful SIP authentication in the SIP core is performed, the register message including an access token and an IP multimedia public identity (IMPU);
• validating the access token based on the register message;
• binding the IMPU with an MCPTT identifier (ID) in case that the access token is valid;
• and
• transmitting, to the SIP core, a response message.

A user equipment (UE) for performing multiple authentications, the UE comprising:

• a transceiver;
• and
• a controller configured to:
• transmit, via the transceiver to a session initiation protocol (SIP) core, a register request message,
• receive, via the transceiver from the SIP core, an authentication challenge message, and
• transmit, via the transceiver to the SIP core, a first register message including an access token to authenticate the UE in the SIP core,
• wherein a second register message including the access token and an IP multimedia public identity (IMPU) that is to be used to validate the access token and bind the IMPU and a mission critical push to talk (MCPTT) identifier (ID) is transmitted from the SIP Core to an MCPTT server in case that a successful SIP authentication is performed based on the first register message.

A session initiation protocol (SIP) core for performing multiple authentications, the SIP core comprising:

• a transceiver;
• and
• a controller configured to:
• receive, via the transceiver from a user equipment (UE), a register request message,
• transmit, via the transceiver to the UE, an authentication challenge message,
• receive, via the transceiver from the UE, a first register message including an access token to authenticate the UE in the SIP core, and
• transmit, via the transceiver to a mission critical push to talk (MCPTT) server, a second register message including the access token and an IP multimedia public identity (IMPU) that is to be used to validate the access token and bind the IMPU and an MCPTT identifier (ID) in case that a successful SIP authentication is performed based on the first register message.

A mission critical push to talk (MCPTT) server for performing multiple authentications, the MCPTT comprising:

• a transceiver;
• and
• a controller configured to:
• receive, via the transceiver, a register message transmitted from a session initiation protocol (SIP) core in case that a successful SIP authentication in the SIP core is performed, the register message including an access token and an IP multimedia public identity (IMPU),
• validate the access token based on the register message,
• bind the IMPU with an MCPTT identifier (ID) in case that the access token is valid, and
• transmit, via the transceiver to the SIP core, a response message.