For our own purposes we are required to set the sip registration expiration to 2 weeks. Moreover, our PBX identify different registrations based on the Call-ID header, which in PJSIP is randomly generated.
Since the app gets closed/killed by the OS the new registration has a new Call-ID and so the registrations start to pile up.
Using this patch we use the same Call-ID for every registration performed by the combination of same {fcm token, sipuser}. We have added another method to the pjsua2/swig binding to set the Call-ID from java code. If this value is not set, the library falls back to the regular way of generating the Call-ID.
The script also increases the PJSIP_MAX_URL_SIZE to 512 defined in sip_config.g because the FCM token may cause the Contact Header to exceed the max default size which was set to 256.