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Title:
【発明の名称】電話呼出し信号の符号化方法及び回路
Document Type and Number:
Japanese Patent JPS60500840
Kind Code:
A
Abstract:
In the disclosed coded telephone ringing signal method and circuitry, audibly distinguishable ringing codes are generated by alternately shifting between at least a pair of single frequency tones at different modulation rates. Other distinguishable ringing codes are generated by changing both the modulation rates and tone frequencies utilized.

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Inventors:
Burger, William Alan
Embury, Dave It Merlin
Singer martin howard
Application Number:
JP50089984A
Publication Date:
May 30, 1985
Filing Date:
January 30, 1984
Export Citation:
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Assignee:
American Telefon and Telegraph Kampani-
International Classes:
H04M1/665; H04M3/02; H04M19/04; (IPC1-7): H04M3/02
Domestic Patent References:
JPS5173803A1976-06-26
Attorney, Agent or Firm:
Masao Okabe



 
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