I've experimented a problem when I've established a call to a cell user using a celulink, and the same user send a FAX when the conversation is active.
Then the cell user doesn't receive audio and then the call drops. The FAX is received OK.
In other cell calls this situation doesn't occurs. It only happens with cell and FAX at the same time with the same user.
I think that the FAX tones over the cell communication are producing this situation, but I've not found anything that confirms it.
Any commentary will be helpful