Patent ID: 7809839

Claim:
A method for a call set-up between mobile communication terminals, comprising steps of: receiving a signaling message for a call set-up with a call-incoming terminal from a call-originating terminal through short data burst (SDB); setting up a traffic channel of the call-originating terminal depending on a first origination signal sent by the call-originating terminal after transmitting the signaling message; receiving a response message of the call-incoming terminal to the signaling message; and setting up a traffic channel of the call-incoming terminal depending on a second origination signal sent by the call-incoming terminal after transmitting the response message, wherein the signaling message is a binary session initiation protocol (SIP) message comprising information about Method (MT), Application ID (AP), and Service Type (ST) for Push-To-Talk session, wherein the step of setting up the traffic channel of the call-originating terminal comprises: receiving the first origination signal from the call-originating terminal; converting the binary SIP message received from the call-originating terminal into a standard full SIP message by a proxy server managing the call-originating terminal; and routing the standard full SIP message to a group talk server (GTS), and wherein the step of receiving the response message of the call-incoming terminal further comprises converting the response message from a standard full SIP type into a binary SIP type if the call-originating terminal is in a dormant state.