Hello Reza
We use http://smslink.sourceforge.net/ with an siemens gms-modem on rs232. The software is pretty simple but dows the job. The main drawback is imo the time needed to handoff an sms to the smsc. But this seems to be a gsm-problem which cannot be circumvent when using a gsm-modem and if you are not sending out a lot of sms it does not really hurt.