Silent Call Telephone Transmitter
This telephone transmitter connects to a standard modular jack. When the telephone rings, a signal is sent to the receiver. Can be used with any Silent Call receiver. Operates on 9 volt battery (included). Comes with 5 year manufacturer's warranty.
More information: http://www.hearmore.com/store/prodView.asp?idproduct=12&idstore=6&product=Silent-Call-Telephone-Transmitter