发明名称 |
Telephone call restricting apparatus |
摘要 |
A telephone call restricting apparatus for preventing toll calls and including circuitry for sequentially decoding the signals representing each digit of a telephone number, storing the first seven decoded digit signals in binary and converting the stored signals into decimal number signals, a comparator for comparing the decimal number signals corresponding to the appropriate digits of the telephone number with permissable local central exchange digits stored in a programmed memory device, a 90 detector and 0/1 detector for detecting long distance calls, an 800 detector and a 555 detector for detecting toll free long distance calls and logic responsive to both the comparator and the detectors and operative to abort unapproved toll calls.
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申请公布号 |
US4188508(A) |
申请公布日期 |
1980.02.12 |
申请号 |
US19780935656 |
申请日期 |
1978.08.21 |
申请人 |
BRINDLE, PATRICK A;BRINDLE, ROBERT G;CHAPPELLE, MICHAEL C;ROGERS, HERBERT I |
发明人 |
BRINDLE, PATRICK A;BRINDLE, ROBERT G;CHAPPELLE, MICHAEL C;ROGERS, HERBERT I |
分类号 |
H04M1/677;(IPC1-7):H04M1/66 |
主分类号 |
H04M1/677 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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