CentOS 5 :: Modem AT Commands To Internal Modem?

I have a Centos 5.4 server running kernel 2.6.18-164.11.1.el5PAE. It has an internal modem, and I need to be able to issue AT commands from a script to the modem. I need to simply dial a number and hang up. The relevant piece of my script is:

[Code]...

With an external modem, this works no problem. With an INTERNAL modem, the call never goes out. I fired up minicom to make sure the modem was working correctly, and if I issue those AT commands from within minicom, everything works great.

While minicom was running, I noticed a peculiar fact: WHILE minicom is running, the script works from the command line, and I can see all the AT commands and OK's in minicom, (minicom acts as a monitor). When I exit minicom, the script stops working. It appears minicom is creating a bridge between the com port and the modem itself. So, what is minicom doing that I'm unaware of?

The server's sole function is to run asterisk as a voicemail server (avaya wanted well into 6 figure territory to implement this....). This script is to dial an avaya FAC to turn the voicemail message lights on and off on the end users' phones.