|Prior to the deregulation of telephony in many countries of the world, it was illegal to make an electrical connetion 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. |
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. A modem would modulate a loudspeaker in the cup attached to the handset"s microphone, and sound from the loudspeaker in the telephone handset"S earpiece would be picked by a microphone in the cup aatached to the earpiece. In this way signals could be passed in both directions.