Adaptation to GSM network of alarm control panels which are equipped with PSTN line communicator to send reports to monitoring station using DTMF based protocols (Contact ID, Ademco Express); the module makes possible the installation of such alarm systems in places where PSTN line is not available but reporting to a monitoring station is required. The module may also be used as phone line substitute, GSM line simulator. By connecting a wired phone device to the module, incoming and outgoing calls can be performed through the GSM network.