I’ve a problem with my Grandstream BT101 IP phone. My phone is behind a NAT, I’m able to use it with many providers, but I’m not able to register it to PBXES. It can make a call but it cannot receive.
In the log you can see the first try to register. The server responds “100 Trying” then “401 Unauthorized”. So the phone tries another registration using the authorization credential, but in this case the server responds only “100 Trying”.
Is there any kind of incompatibility between Grandstream phones and PBXES?