In earlier telephones the transmitter was mounted directly on the telephone itself, which was attached to a wall at a convenient height or affixed to a desk stand.
The handset of a cordless telephone contains a radio transceiver which relays communication via a base station that is wired to the telephone line. A mobile phone does not require a base station and communicates directly with a cell site in specially designated frequency bands.
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A graphic symbol that designates a handset is used on cordless and mobile phones to specify placing or ending a telephone call. Usually a button with green upright (off-hook) handset icon is used for starting a call, and a red lying-down (on-hook) handset is used for ending a call. Unicode provides the U+1F4DE 📞 TELEPHONE RECEIVER symbol.