Abstract: A security system comprises a signal transmitter (1) with a first sensor (2) for conveying status information to a receiver (3) via a telecommunication channel (4), the signal transmitter being preferably built into a telephone set and the telecommunication channel preferably comprising a subscriber line in a regular telephone network. A second sensor having a higher sensitivity than the first sensor, is arranged to be influenced by the same alarm situation as the first sensor to transmit alarm information to the receiver via the telecommunication channel, and a restoring circuit (6) comprising time measuring components (7, 8) with an activation input (9) connected to the second sensor is, within a time slot of a predetermined length arranged for the transmittal of the status information and the alarm information, arranged to always transmit restoring information regarding the alarm information to the receiver.