Having some issues with Android endpoints trying to route over IPv6 it seems. I disabled IPv6 completely in CentOS but it still seems to happen. When I do a PJSIP SHOW ENDPOINTS I see the IPv4 associated with the Android client. But when connecting a call I see this error and no audio is passed.
[2020-03-24 13:07:27] WARNING: acl.c:972 ast_ouraddrfor: Cannot connect to 2607:fb90:6b0d:1234:1234:123:1234:1234: Network is unreachable
> 0x7f19304c16a0 -- Strict RTP learning after remote address set to: [2607:fb90:6b0d:1234:1234:123:1234:1234]:7078
-- Channel PJSIP/7275555555-0000230c joined 'simple_bridge' basic-bridge <e04b6b62-02b7-49e2-86ba-770e0e8f4a5d>
-- Channel PJSIP/103-0000230b joined 'simple_bridge' basic-bridge <e04b6b62-02b7-49e2-86ba-770e0e8f4a5d>
-- Channel PJSIP/7275555555-0000230c left 'simple_bridge' basic-bridge <e04b6b62-02b7-49e2-86ba-770e0e8f4a5d>
-- Channel PJSIP/103-0000230b left 'simple_bridge' basic-bridge <e04b6b62-02b7-49e2-86ba-770e0e8f4a5d>
== Spawn extension (trk-2-dial, 17276560484, 18) exited non-zero on 'PJSIP/103-0000230b'
I have modified IPs and phone numbers for privacy.
So it would appear that with IPv4 running out cell carriers are starting to issue IPv6 IP addresses. I tried everything I could to disable IPv6 on both the host and client to no avail. After reading more and more about IPv6 and how everything has to move that way anyway I decided to dive into configuring IPv6 on my Azure VPS which wasn't an easy task. In the end I have a dual stack IPv4/IPv6 setup working properly and media routing over IPv6 when needed.
Honestly I won't post any more than the link that got me started because there is so much to learn about how Azure utilizes IPv6 currently that anyone who is going to use it needs to understand how it works through trial and error. It doesn't directly use IPv6 but load balances it back to the IPv4 adapter. Good luck to anyone who wants to take this on with an existing Azure VM. If you are starting fresh you can use the commands provided in the link before deploying VitalPBX on top of your flavor of linux.