Patent ID: 8830898

Claim:
A method for establishing a press-to-talk (PTT) session between a first terminal serviced by a first communication system and a second terminal serviced by a second communication system, in which the first communication system and the second communication system are interconnected by a transmission link, the method comprising: receiving a transmission demand message (TX-DEMAND) from the first terminal at the first communication system; sending, at the first communication system, a transmission granted message (TX-GRANTED) to the first terminal and a transmission demand message (TX-DEMAND) to the second communication system if a communication channel is locally available for the press-to-talk session, wherein locally available is available at the first communication system and at an interface between the first communication system and the second communication system; simultaneously to sending the transmission granted message (TX-GRANTED), receiving transmission packets at the first communication system from the first terminal and relaying the transmission packets to the second communication system; and then continuing relaying transmission packets to the second communication system if a transmission granted message (TX-GRANTED) from the second communication system in reply to the transmission demand message (TX-DEMAND) at the first communication system is received.