| 摘要 |
PURPOSE:To enable to obtain the similar function as a keyed public telephone set, by constituting that it is taken as registrated public transmission when the secret number is during registration by the resistered personnel and it is treated as conventional telephone transmission when the secret number is released. CONSTITUTION:In calling the registrated public telephone set 11 as public telephone call, the caller first dials the secret number preset in this telephone set 11 and registrate it in the cryptograph section present in the analyzer 13. Since the secret number is registrated in the exchange station, the call from the telephone set 11 with this state is all of public telephone service. In case of conventional telephone service, the registrated personnel releases the secret number registrated in advance. With this state, the call is subject to conventional telephone service. Thus, the key detection circuit is unnecessary in the public telephone sets and the constitution of each public phone is made simple. |
