GSM With PIC?

Hi
I would like to know how a GSM module + PIC can send location signals?
Is there a seperate service from some company involed in this?
Can any GSM module be used? I just bought TC35i & Sim300 to experiment, can either of these be used for this purpose.

AND lastly, where can I get more info/help if I try to make this project.

Thanks (a lot) :)

You can download my project (I did use Siemens tc35i gsm modem) to have some inputs on how to start.

http://techni.caliti.es/blog/2008/12...ontroller.html

Al.