The CallFinder ® GSM cellular gateway enables small to medium sized businesses to take advantage of lower cost wireless networks to provide a substantial savings in their overall telephone bill. It connects to a PBX trunk line, PBX extension line, or a single PSTN line and routes incoming and outgoing calls through a GSM wireless network. Equipped with both FXS and FXO interfaces,the gateway offers a wide range of potential applications.When connected to a PBX or Key Telephone System,it converts an expensive PSTN-to-GSM call into a direct mobile-to-mobile call. When connected to an analog telephone, it can serve as the primary voice network for small remote offices or other locations that don’t have a fixed line infrastructure. In addition, it can be used as an alternate route for voice communications in emergency situations.