In some cases, the application calls for a "power fail" notification via SMS. Normally, this necessitates a bulky external battery to be used. It sometimes happens that the criminals kick open the enclosure and cut all wires to the GSM device, including the battery, before an outgoing SMS has the time to actually go out. The answer is an internal battery option for the GSM Commander. This allows your GSM Commander to respond to power failures without needing an external battery. Any SMS that was queued before the battery wires were disconnected, can of course still be transmitted normally.