Abstract: A data transmission apparatus includes a telephone line interface, a telephone line fault detector, DTMF and pulse dialing detectors, data pulse and tone detectors, a tone generator, a microprocessor controller, and a radio transmitter. The line fault detector monitors the phone line for a fault. The DTMF and pulse dialing detectors detect the telephone number dialed by the dialer. The microprocessor directs the radio transmitter to transmit a message indicting a telephone line failure if a line failure is detected. When a line failure is detected, the microprocessor causes the telephone line interface to disconnect the telephone dialer from the telephone line and to "capture" the dialer by coupling it to the data pulse and tone detectors and the tone generator. The data pulse and tone detectors and the tone generator emulate telephone line communication between the dialer and a monitoring station. The data received from the dialer is transmitted by the radio transmitter as an RF data burst.