SYSTEM FOR PREVENTING NO-COIN CALLING IN PUBLIC TELEPHONE

摘要

The device prevents public telephone from illegal usage without injection of coin or telephone card. A sending signal module established in the public telephone detects injection of coin or telephone card, generates a unique signal corresponding to the public telephone, and sends the signal to a division device in the telephone office. The receiving circuit of the device detects and examines the signal. If the signal is correct, the subscriber line is connected to local telephone line by the device.