Ring signal discriminator

• US 4,720,853 A
• Filed: 03/09/1987
• Issued: 01/19/1988
• Est. Priority Date: 07/05/1985
• Status: Expired due to Term

• Current Assignee: Aspect Software Incorporated
• Original Assignee: Melita Electronic Labs Incorporated
• Inventors: Szlam, Aleksander
• Primary Examiner(s): Dwyer, James L.
• Application Number:
  US07/003,643
• Time in Patent Office: 316 Days
• Field of Search: 379/373, 379/374, 379/375, 379/376, 379/386, 379/82, 379/211
• US Class Current: 379/382
• CPC Class Codes: H04M 1/652 Means for playing back the recorded messages by remote control over a telephone line H04M1/658 takes precedence
• CPC Class Codes: H04M 1/654 Telephone line monitoring circuits therefor, e.g. ring detectors
• CPC Class Codes: H04M 1/658 Means for redirecting recorded messages to other extensions or equipment
• CPC Class Codes: H04M 3/54 Arrangements for diverting calls for one subscriber to another predetermined subscriber based on the calling party profile H04M3/42059; based on location H04M3/42348; based on presence H04M3/42365; to voice mail H04M3/53308
• CPC Class Codes: Y10S 379/903 Password

Abstract

An improvement to automatic answering and call forwarding features used in telephone communications which allows a user to remotely activate, modify, and deactivate these features. The improvement describes a transformerless means for coupling signals to and from the telephone line without compromising the operation of the telephone line. The apparatus employs a microprocessor controller (11) with memory (12), a tone encoder (15), a tone decoder (14), a voice synthesizer (16), a timer (13), a cassette interface (17), an RS232C interface (20), a switching matrix (21), and a line interface (22). Audio, pulse dial, and tone signals are routed among the components and the telephone line (51) by the switching matrix (21) and line interface (22). The line interface (22) provides a transformerless means for coupling signals to and from the telephone line (51) and also analyzes the status of, and signals present on, the telephone line (51).

Claims

1. A ring signal and dial pulse detector for detecting and discriminating among normal ringing signals, call forward reminder ringing signals, and rotary dial pulses on a telephone line and comprising:

a capacitor for blocking D.C. voltages on said telephone line;

optocoupler/isolator means connected across said telephone line and responsive to an input signal for providing a first output signal corresponding to, but electrically isolated from, said input signal;

low pass filter means for eliminating high frequency signals and noise transitions in said first output signal;

voltage comparator means for providing a second output signal responsive to the output voltage of said low pass filter means;

retriggerable timer means responsive to said second output signal for providing a third output signal which is retriggerable and which continues for a predetermined period after the last transition of a predetermined polarity of said second output signal; and

processor means responsive to the pulse width and repetition rate of said second and third output signals for providing a fourth output signal indicative of whether said input signal is a normal ringing signal, a call forward reminder ringing signal, or a rotary dial pulse.

2. The apparatus of claim 1 wherein said voltage comparator means has a predetermined hysteresis voltage.

3. The apparatus of claim 1 and further comprising:

a rectifier means, connected between said capacitor and said optocoupler/isolator means, and operative to convert bipolar signals into unipolar signals.

4. The apparatus of claim 1 wherein said retriggerable timer means is a retriggerable monostable multivibrator.

5. The apparatus of claim 1 and further comprising:

voltage reduction means between said optocoupler/isolator and said telephone line for altering the sensitivity of said optocoupler/isolator.

6. A method for detecting and discriminating among normal ringing signals, call forward reminder ringing signals, and rotary dial pulses on a telephone line comprising:

blocking D.C. voltages on said telephone line;

providing a first output signal corresponding to, but electrically isolated from, an input signal on said telephone line;

providing a filtered signal by low pass filtering said first output signal to eliminate high frequency signals and noise transitions in said first output signal;

providing a second output signal responsive to the output voltage level of said filtered signal;

providing a third output signal which is responsive to transitions of a predetermined polarity in said second output signals and which continues for a predetermined period after the last transition of said predetermined polarity of said second output signal; and

analyzing the pulse width and repetition rate of said second and third output signals for providing a fourth output signal indicative of whether said input signal is a normal ringing signal, a call forward reminder ringing signal, or a rotary dial pulse.