Stupid question: Every cell phone or i-phone or j-phone or whatever offers a short or long DTMF tone sending option. It's also never the standard setting for the phone. Most people never notice, but when interfacing with non-cell terminations, there is the need for DTMF signaling.

Could it be that it's set to short so that some of the digits sent are being missed? Perhaps only one digit is being detected, as in the option to send a fax? Does your auto attendant offer a single-digit option to send a fax?

Sorry for all of the questions, but this sounds like a problem that can exist with any system if the cell phone isn't sending DTMF tones that are long enough for the system to detect.

Ed Vaughn, MBSWWYPBX