a device for rerouting the report call of an alarm system to another telephone number through the interruption of the alarm system &# 39 ; s out - dialing process , includes two electronically controlled switching devices that allow the device to momentarily isolate the alarm from the phone line . switches are operated under microprocessor control , for causing dialing of the new phone number by the generation of dtmf tones by a dtmf generator operating under microprocessor control . triggering of the report call rerouting process is keyed to the presence of two conditions : one being loss of voltage from the handset lines , and the other being presence of dialing activity , either dtmf tones or pulse - dialing pulses on the telephone line . the device will reset itself after the telephone has been held in the on - hook condition for a predetermined interval by the alarm system , to allow the device to reroute subsequent report call attempts if initial attempts to connect are unsuccessful .