长途电话锁控电路陆承法现代通信对长途电话锁控电路的要求是：锁控时，不仅首位号码“０”发不出去，就是“０”后面的号码也发不出去，甚至连存储器里的“０”打头的电话号码取出来也不允许发出去。针对这些新的要求，如何实现锁控？现介绍两种简单实用的电话机长途电话... Long-distance telephone lock control circuit Lu Chengfa Modern communication requirements for long-distance telephone lock control circuit are: lock control, not only the first number “0” can not send out, that is, “0” behind the number can not send out, and even the memory “ 0 ”at the beginning of the phone number taken out nor allowed to send out. For these new requirements, how to achieve lock control? Now introduce two simple and practical telephone long distance calls ...