I'm trying to send a FAX using a GSM cell phone. My laptop PC dials the correct number, as shown on the cell phone display. But, the call does not go through; the FAX, or any other number being called, never answers. Are there any codes that I need to add as prefixes to the phone number? I am able to make voice calls using the PC to dial the phone. I have the cell phone connected to my PC using a USB cable. My OS is Windows XP. The cell phone modem - Motorola T720 - is working and responds properly to diagnostic commands. I have talked to Cellular One and Motorola for hours on this subject - each blames the other.