Fast inter system push to talk operation

摘要

Method for establishing a press-to-talk (PTT) session between a first terminal (16) serviced by a first communication system (10) and a second terminal (17) serviced by a second communication system (11), in which the first communication system (10) and second communication system are interconnected by a transmission link (12). The method includes receiving a transmission demand message (TX-DEMAND) from the first terminal (16), sending a transmission granted message (TX-GRANTED) to the first terminal (16) and a transmission demand message (TX-DEMAND) to the second communication system (11) if a communication channel is locally available for the press-to-talk session, receiving transmission packets from the first terminal (16) and relaying the transmission packets to the second communication system (11), and if receiving a transmission granted message (TX-GRANTED) from the second communication system (11) in reply to the transmission demand message (TX-DEMAND), continuing relaying transmission packets to the second communication system (11).