Chad,

I know nothing about the Allworx system. Basically skimming your post, you said it is a random problem that only he is having. Shot in the dark, but we have had that happen with other systems and it turned out to be that the employee was holding handset under chin or turning their head while talking. Obviously callers couldn't hear as well unless the handset was being held properly and user is speaking directly in to the microphone/handset. Probably not the case w/ your scenario, but stranger things have happened and my guess didn't cost you anything.

Rick

BTS