Abstract: A method for deploying a link between at least one security system and an alarm control unit. Each security system is fixed in position. A mobile terminal, having a frequency-spreading key and a short-range wireless signal transmitter having a transmission range less than or equal to the communication range of a wireless local network, is positioned close to a fixed security system. The frequency-spreading key is transmitted to the fixed security system via short-range wireless signals. The alarm control unit is fixed in position at a distance from at least one security system that is greater than the transmission distance of the short-range wireless signal transmitter. A security message is communicated between a communication channel of at least one security system and the alarm control unit, implementing spectrum spreading depending on the spreading key.