Dell PC Fax Program Not Detecting Modem

I have a Dell PC w/Vista 32-bit O/S and 926 AIO printer. Verizon recently provided a new modem/wireless router that I can't find on the computer. The problem is that when I use Dell PC Fax, everything functions perfect until sending...the program is automatically detecting a different modem. The change modem option provides no real option to change it...it detects modems on its own and always finds this same one. I have located this modem through the control panel, but it is not the one from Verizon. Bottom line is the Dell PC Fax program fails to send. Can anyone help?