We setup a sip trunk through a MBG to a 3300.  Everything works, but all incoming calls use double the licenses.  Eg, one incoming calls shows 2 licenses used.  Mitel says the reason is the the SIP provider is sending the option supporting FAX on the sip trunk, so the MBG is using a sip license for voice and one for fax, even if its just a voice call.
Anyone know how to stop it?