Greetings,
Here, the steps you can follow to get an interface to your cell phone:
1. get the data cable of your cell phone... serial / usb
2. based on cable data type, you must search adecuated code for interface the phone with the SO. The easy way is the serial one.... usb is more complicated, because you need a general driver or programming your own driver
3. read a lot about the AT Commands, search the AT Commands for your specific phone... this is the way to control your phone...
Good luck