Hang up on outbound dial

I’m having an issue where my Polycom phones (330,335) are having issues occasionally while dialing out. I even tried rebuilding the entire phone system and the bug will not go away. It gets resolved temporarily if I remove the phone’s config and rebuild it, but after reloading asterisk the issue comes back on a few phones.

I’ve watched the CLI when this event occurs and the following errors are thrown:
WARNING[9619][C-00000059]: chan_sip.c:15745 __set_address_from_contact: Invalid contact uri (missing sip: or sips:), attempting to use anyway
WARNING[9619][C-00000059]: chan_sip.c:15758 __set_address_from_contact: Invalid URI: parse_uri failed to acquire hostport

I am at a loss for what to do. Any ideas?

You should start posting sip debug output. And what Asterisk version are you using ?

I’m on version 11.5.1. I don’t have debug logs at the moment because the issue is momentarily at bay. However, whenever I change something and reload asterisk. That is when the problems usually start. I’m not sure whether it is asterisk or the phones, because as soon as I reformat the phone and have it reload the configuration, the problem resolves.