Carterfone

The Carterfone is a device invented by Thomas Carter. It manually connects a two-way radio system to the telephone system, allowing someone on the radio to talk to someone on the phone. This makes it a direct predecessor to today's autopatch.

The device was acoustically, but not electrically, connected to the public switched telephone network. It was electrically connected to the base station of the mobile radio system, and got its power from the base station. All electrical parts were encased in bakelite, an early plastic.

When someone on a two-way radio wished to speak to someone on phone, or "landline" (e.g., "Central dispatch, patch me through to McGarrett"), the station operator at the base would dial the telephone number. When callers on the radio and on the telephone were both in contact with the base station operator, the handset of the operator's telephone was placed on a cradle built into the Carterfone device. A voice-operated switch in the Carterfone automatically switched on the radio transmitter when the telephone caller was speaking; when he stopped speaking, the radio returned to a receiving condition. A separate speaker was attached to the Carterfone to allow the base station operator to monitor the conversation, adjust the voice volume, and hang up his telephone when the conversation had ended.

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