TL;DR version is that callcentric.com has multiple A records, so Asterisk registers with different servers over time. This seems to cause Asterisk to return a 401 UNAUTHORIZED to INVITES, possibly because the peer IP is not getting updated when the registration IP changes.
Is there a way to verify that this is, in fact, the problem. sip show peers will show me peer IP addresses, but I haven’t been able to find a way to get sip show registry to show IP addresses.
Assuming that this is the problem, what can I do about it?
(I am running Asterisk 1.8.32 on CentOS 6.)