Having an increasing issue where various PBX’s are not answering calls inbound from mobile phones.
It is intermittent, but have had a trace done on our SIP trunk Provider. Who sees an error 500 in their pcap trace
we have no reports of this happening from landline type calls only Mobiles.
Just guessing, when the mobile has a VoLTE connection, Asterisk rejects the call because of a codec mismatch.
If you can cause the trouble by calling from a specific mobile, at the Asterisk command prompt type pjsip set logger on
(or sip set debug on if you are still using chan_sip)
paste the Asterisk log for a failed call at pastebin.freepbx.org and post the link here.
If you cannot cause the trouble at will, see
for various ways to capture traffic continuously until trouble is reported.