Telephone for inhibiting specific calls dialed by an audible ton

Details Telephone for inhibiting specific calls dialed by an audible ton Telephone for inhibiting specific calls dialed by an audible ton

1994-01-26

1995-08-08

Matar, Ahmad

Telephonic communications

Call or terminal access alarm or control

At substation

379356, H04M 338

Patent

active

054406226

ABSTRACT:
A telephone capable of controlling an expensive long distance call or international call from an audible tone generator through the telephone's handset. When the handset is lifted, an off-hook signal is output from a hook switch and a CPU outputs an internal hook signal to close a line switch. When a dialed number is input from the telephone's key board, the CPU checks the first digit of the dialed number. When the first digit is "0", the internal hook signal is output to release the line switch, otherwise a line loop is kept as it is to make a dialing possible. In turn, when a DTMF signal corresponding to the dialed number is input from a DTMF generator via the handset, a DTMF receiver interprets first digit of the dialed number and sends it to the CPU. When the first digit is "0", the CPU outputs an on-hook signal to release the line switch, otherwise the line loop is maintained to make the dialing possible.

REFERENCES:
patent: 4297534 (1981-10-01), Epstein et al.
patent: 4947422 (1990-08-01), Smith et al.

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