It's as simple as sending the initialize string to the serial port write vi (or visa i guess). I wrote something years ago at my last company. It was a crude mass paging program to use the modem to send pages to a list of numbers. But crude meant simple and to initialize the modem i would write something along the lines of 'ATM0' to the serial port where the modem is located. The modem's manual should give you a recommended initialize string as well as a list of other supported commands and how to use them. For insance, turning on the speaker so you will be able to hear it dial.
Good luck,
Jared
