Call Initiated From Radio Network - R&S M3SR 4100 Series Operating Manual

M3SR Series 4100
and "RINGING". If a SIP session has been successfully established or terminated, the VoIP
gateway radio signalizes to the radio network with the proprietary messages "CONNECTED"
or "RELEASED", respectively.
When receiving state signalling from the VoIP gateway radio, radio units in the radio network
locally generate acoustic signals and do not send acknowledgments back to the VoIP gate-
way radio to avoid collisions.
Radio Network Receives a Call
When the VoIP gateway radio receives an "INVITE" request, it sends an "INCOMING" mes-
sage to the radio network. If the automatic call accept delay is defined as zero or expires be-
fore an endpoint answers the incoming call, the VoIP gateway radio signalizes to the radio
network that it has accepted the call by sending a "CONNECTED" message to the affected
radios (see Figure 5.35).
If a radio answers the incoming call before the automatic call accept delay has expired, this
radio sends an "ACCEPT" event message to the VoIP gateway radio. Once the VoIP gate-
way radio has received the "ACCEPT" message, the VoIP gateway radio signalizes to the
radio network that the incoming call has been accepted by sending a "CONNECTED" mes-
sage (see Figure 5.36).

Call Initiated from Radio Network

When a radio wants to call out of the radio network to a VoIP user on the IP network side, it
sends a "DIAL" message to the VoIP gateway radio, giving information about the called party.
Once the VoIP gateway radio has received the "100 Trying" and "180 Ringing" responses
from the IP network side, it sends the respective proprietary signals "TRYING" and "RING-
ING" to the radio network.
When the VoIP gateway radio receives a "200 OK" response from the external VoIP user, it
broadcasts the proprietary signal "CONNECTED" to the radio network.
Terminating the Session
When a radio wants to terminate the call session, it sends a "HANG UP" request to the VoIP
gateway radio (see Figure 5.35). The external VoIP user can also terminate the call session
with the VoIP gateway radio by sending a "BYE" request (see ). In either case, the VoIP gate-
way radio has to signalize to the radio network that the session has ended by sending a
"RELEASED" message to all affected units inside the radio network.
5.124
SIP – Useful Information for System Integration
Operating Manual 6172.5808.02 – 01