Generally available in the 1980's, the cordless telephone has become very popular. These are telephones which connect to standard telephone lines and are, therefore, not to be confused with mobile or cellular telephones.
The cordless telephone operates in much the same way as a conventional telephone apart from one important aspect; the handset is not attached to the main body of the telephone by wires but in contact by radio waves.
As the caller speaks into the handset, voice signals are transmitted to the receiver in the main telephone unit (usually called the base station). These are then converted back into analogue voice signals for transmission down the telephone line. The incoming voice goes through the opposite process of conversion to a radio signal which is transmitted to the handset before being converted back into an audio signal for playback through the earpiece.
These cordless telephones allow a great deal of freedom to the user with ranges now available up to 500 metres between handset and base station.
