UNIVERSAL - our telephone ringer amplifier is compatible with all analogue telephones with a standard BT style line socket, including telephones connected to the BT Digital Voice broadband. NOT SUITABLE for digital or IP/Internet phone systems (PABX). PLUG & PLAY solution - we have designed out CEA-40 call alert to be as simple to install as possible - you will be able to do it yourself with no specialist installation or batteries required. Plugs directly into a standard BT telephone wall socket and your telephone. NEVER MISS A CALL AGAIN - the CEA-40 Tone ringer is an ideal solution for the hard of hearing, or for use in noisy environments. It will ring at volumes up to 95dB and as long as the phone is ringing it will flash brightly to catch your attention and ensure no calls go unanswered.
eBay