Meng Wang shows how to have your computer make calls with your GSM cell phone in VB.Net. If you're interested in how this works, he has 3 articles on Code Project.
- Part I - Retrieve Phone Settings
Part II - Send SMS(link dead 7/8/2008) Part III - Dial, Answer, Reject(link dead 7/8/2008)
The Coding4Fun Hoilday guide has a bare bones USB GSM cellphone (GM862-GPS Evaluation Cell phone Kit – USB) from Spark Fun if you're interested in this project.