If the panel is pushing out what the OP states as sounding like DTMF tones, it's not the panel most likely, say 99% certainty . The IPdatatel unit is a data capture unit, so this points to them being the issue. No compatibility issues if the OP didn't do anything to the HAI.
The issue is the 3rd party vendor here, IPdatatel or the VZW connection through IPdatatel.
The issue is the 3rd party vendor here, IPdatatel or the VZW connection through IPdatatel.