I'm using zoiper as a solution for mobile extension on android phones having marshmallow 6 OS and they are motorola e 4g 2nd gen and have all the updates installed (apps and OS). All the phones register as IAX extensions to an Asterisk server. While the screen is on or shortly after the screen goes off I can receive calls without problem, after some time when the phone is called it does not ring, although the caller hears it is ringing. I have increased the ring time and found out that the phone starts ringning after 4 to 5 rings about 15-20 secs. Is there something I can do? My PBX uses UDP.
Thank you and best regards