I have these repeaters connected to my old Siemens Gigaset SX353 ISDN. You have to remember that one (Base Settings - Settings - System Settings - special function - Repeater) the repeater function based activated first. Then you learn the repeater like a normal mobile terminal to the base and then looks for a nice place in the house, away from the base, but so that the LED indicating that it still has a connection. For me, the base is on the first floor and the repeater is added to the ground floor. I have DECT coverage now from the basement to the top floor and the entire garden. Roaming (during the conversation I walk through the house and the handset switches between base and repeater) works problemlos.Top product !!