Thanks Keke for the great software. Just wanted to let the community know that the unlocked Zoom 4597 3G+ Freedom Modem (USB) works. It is available for less than $70 US at a number of online stores. My current setup is on a MacBook Pro with Snow Leopard, but I plan to move it to a MacMini once I finish developing my "companion" software.

One trick, I find I have to run and stop the included "3G+ Freedom" software to get the drivers going after rebooting, or removing and reinstalling the modem. Then I can use the SMStools3. There may be a simple or not so simple way to get around that, but for now I just have my companion software launch the "3G+ Freedom" application, wait one minute, shut it down and then go about its business. Works for me. Normally it will be up and running 24/7 so this won't happen often.