Acoustic coupler
In telecommunications, the term acoustic coupler has the following meanings: The link is achieved through acoustic (sound) signals rather than through direct electrical connection. Prior to the deregulation of telephony in many countries of the world, it was illegal to make an electrical connection to the telephone network. Also, in many households, telephones were hard-wired to wall terminals before connectors like RJ11 and BS 6312 became standardised. With the increased use of computing, acoustic couplers were used to connect modems to the telephone network. Speeds were typically 300 bits per second, achieved by modulating a carrier at 300 baud. The first such device was the ACOUSTIC DATA COUPLER 300 MODEM from 1968. Usually, a standard telephone handset was placed into a cradle that had been engineered to fit closely (by the use of rubber seals) around the microphone and earpiece of the handset.
