GSM modems allows to set up a gateway between IP network and a GSM network, e.g. to use SMS to communicate.
In most cases a common SIM card is inserted into a GSM modem; for the GSM network it uses, GSM modem looks like a mobile device. Depending on model and manufacturer, GSM modem can use one or more SIM cards, thus allowing different GSM networks interconnection and/or using more numbers within the same network.
Network Monitoring with SMS alerts
SMS over GSM modem alert allows sending SMS (text message) over GSM modem or phone attached to the computer.