发明名称 |
Line-powered detection of call progress tones |
摘要 |
The invention provides a method for detecting a call progress tone on a pair of telephone conductors (the telephone line). The level of energy stored in an energy storage device is continually checked. When the level of energy of the energy storage device is below a threshold, the system couples the telephone line to an off-hook impedance. While coupled to the telephone line, the system charges the energy storage device using current drawn from the telephone line, and the system detects the presence of the call progress tone on the telephone line.
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申请公布号 |
US5790653(A) |
申请公布日期 |
1998.08.04 |
申请号 |
US19970784454 |
申请日期 |
1997.01.16 |
申请人 |
VOICEWAVES, INC. |
发明人 |
FAIRBANKS, SR., JOHN P.;FAIRBANKS, SCOTT M. |
分类号 |
H04M3/537;H04Q1/444;(IPC1-7):H04M19/00 |
主分类号 |
H04M3/537 |
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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