You should use AT command set used for modems. Search for AT command set for GSM with google, etc. I think sending SMS is quite complicated. :?
Try this:
**broken link removed**
or AT modem standarts for mobiles
**broken link removed** (you have to register to download)
Other important point is the connector. Sometimes it is hard to find a cable and connector for computer communication. I have used ericsson chatboard socket for old models with max232 level converter. :lol: