Patent ID: 10244009

Abstract:
A method for initializing a call for a mobile terminal including PTT applications on an IP-WAN cellular network, the method including, for each user of the mobile terminal connected to an IP-WAN modem intended to register for a group call: upon starting up the IP-WAN modem, connecting the mobile terminal to the IP-WAN cellular network; when a PTT client is active and has obtained an IP address of a PTT server, initiating by the PTT client a procedure for registering a SIP with the PTT server on a default IP-WAN carrier; performing by the PTT client a procedure for affiliation to a call group with the PTT server on the default IP-WAN carrier, and as soon as the procedure for affiliation to the call group is performed, executing an “INVITE” (SIP) procedure to RTP resources at an application level on a PTT side and on the PTT client side, to allow the establishment of the RTP session after the affiliation of the PTT client to the group.