[ERROR ] PHN: Dispatcher::SendRequest: No credentials set for identity 1
[CRITIC] SIP: Registrar PA.IT@xxxx.com refused with code 401
[CRITIC] SIP: Will not try to reregister because login credentials were rejected by Lync!
From the logs, it seems your registrar is rejecting the user credentials for identity 1 on the PA1. Could you double check the settings are correct ?
What is the exact firmware version you are using on the PA1?