Call2Teams - Customer
This error is usually seen on incoming call failures and is appended with .'..and PNH got delivery errors from all of them'.
The SIP error code is presented as a 480 SIP error. 480 errors usually suggest a networking issue.
Explanation of Behaviour
This is Microsoft advising us that it has been unable to route to the endpoints it is expecting to find.
There is not much detail on the precise explaination for this error when searching the web but any mention of the term 'Endpoints' from Microsoft refers to the end Teams Client. If these endpoints are invisible because of a network issue, for example, it is between Microsoft and the end user's Teams client.
Unfortunately we are unable to see anything beyond the message being returned to us by Microsoft. If subsequent calls are successful then it would suggest the issue was temporary. However, if the issue persists, then take a look in the Microsoft Call logs to ascertain whether the call got that far and potentially raise a case with Microsoft.
Accessing the Microsoft Call Logs