I have just bought a Panasonic KX-TG6523E trio of telephones. Only the base unit plugs into a telephone socket, the other two satellite phone just plug into their chargers. These three phones are situated in the lounge, study and kitchen. Is it possible to plug in a different cordless phone (BT Studio 1100) and its charger into another telephone socket in the bed room? Will an incoming call cause all four phones to ring and will the BT phone interfere in any way with the performance of the Panasonic phones?