The Sendata 700B Series acoustic coupler enables data transmission at 300 bps and features full duplex  answer/ originate using the CCITT V21 frequency standard.

An acoustic coupler is a device that allows a computer to transmit data over a standard telephone line by converting digital signals into audible tones and sending them through a telephone handset's speaker and microphone. The coupler physically holds the handset in rubber cups to minimise background noise and ensure sound transmission. 

Our Sendata 700B Series acoustic coupler has serial number 2256 and comes complete with a Tandy Acoustic Coupler Manual. It was generously donated to our collection by Peter Martin.