A: You can go to the Front End Server:
C:\Program Files\SipInterceptor folder and right click on the Wsp.Anywhere365.SipInterceptor.exe
Now choose for properties and then review the Details tab.
A: Most likely your Global VoicePolicies are limited. By default the UCC gets the Global VoicePolicies, and will use these to do the Call.
Grant the all the UCC ApplicationEndpoints a VoicePolicy, which are able to do a PSTN Call.
A: Yes you can change this by doing the following steps:
Navigate to the Audio directory
6.3: C:\Program Files\Anywhere365\Core\UCC\
6.1: C:\Program Files\Anywhere365\Core\
5.0: C:\Program Files\UCC\
Note Create a backup.
Restart the UCC Service