IP trunk sporadically losing registration

Hello. I’m having a new problem where my IP trunk registration to voipstreet.com suddenly is lost. I try to do a sip reload and it doesn’t resolve the issue. The only way I’m able to get registration back is by changing the default route to a different interface. This works sometimes for 5 minutes, sometimes for 12 hours, but it will fail again and I will have to again change the default route to get it back. I’m really stumped and this is causing a lot of headaches. If anyone has any idea of what may be going on I would really appreciate some input. Thanks!

Sounds like a stateful router forgetting its states.