Receciving Calls

This section details how an Incoming INVITE from the PBX wakes up the softphone and hands over the incoming call.

Step1

Push server receives INVITE from PBX

Step 2

Push server matches INVITE to registered devices,depending on if it is an Apple or Android device an API call is made to Apple APNS or Google FCM (Firebase cloud messaging)

Step 3

Push Notification sent to device.

Step 4

Device wakes up and makes a secure TCP connection to the Push server.

Step 5

The Push server then forwards the INVITE to the device.ALL further SIP signalling from the device then passes over this secure TCP connection to the Push server which is then forwarded to the PBX and vice versa.

Step 6

Audio and Viedeo RTP packets pass directly between device and PBX.

What is not shown when the device wakes up is the registration flow.This has been covered in the sections on Push registration modes and the flow will depend on which registration mode has been selected.