The Global System for Mobile Communications (GSM) is an international digital cellular telecommunications standard.
Many modern GSM modems are "plug in and play" devices which can be connected directly to the serial port of a PC or laptop computer through the RS232 interface.
These devices are generally used for applications such as telemetry, Wireless Local Loop (payphones) or as part of a fleet management system.
GSM modems can also be a PC Card installed in a laptop or a standard GSM mobile phone with the appropriate cable and software driver to connect to a serial port on a computer.
A GSM modems are used to enable wireless communications using the GSM standard, allowing SMS, MMS and voice messages to be passed between remote locations and centralised stations.
In order to utilise this technology and allow for it to be inherently mobile, any such modem used in this kind of environment needs reliable back-up power in the case where external power (such as a vehicle battery) fails. Due to the nature of these devices, it is likely that they will run from an external power supply for the majority of there operation and back-up power will not be called on regularly. It is therefore vitally important that the battery used for this back-up power has a low self-discharge rate and is guaranteed to function correctly even with extended periods of inactivity.
Because of these reasons, Lithium technology is being used as its characteristics match up best with the environment of remote GSM devices. Another advantage of Lithium chemistries is the extended operational temperature characteristics when compared to other battery technologies. Because external power failure is likely to be due to extreme conditions it makes them the perfect choice for these devices.
