GSM Modems are industry type devices, and may not fully support some of the new SIM cards created for modern mobile phones. If you during installation of the SysManSMS Server see such problems, the Server will stop, and a typical error code in the SysManSMS.log file will be:
ERR-120-1 Can't get number of SIM locations in unit
You should first of all try to upgrade your SysManSMS Server to the latest release. If this does not help, you may have a unsupported SIM card.