Method and apparatus for processing coded information received through a telephone line during the inter-ringing periods

A method for processing coded information received through a telephone line in a telephone system of the Touch-Tone type in which the system transmits ringing signals separated by inter-ring periods, the method comprising the steps of:

• (A) normally sending from a calling subscriber signals corresponding to the phone number of a called subscriber;
• (B) when the calling subscriber receives corresponding signals indicating that ringing signals are being sent to the called subscriber in response to the establishment of a ringing circuit between the calling and the called subscribers, sending from the calling subscriber at least one pre-established code tone signal during at least one of the inter-ringing periods;
• (C) suppressing at the called subscriber the ringing signals received during the ringing periods while letting through the code signal;
• (D) amplifying said code tone signals;
• (E) decoding said amplified code tone signals and comparing each said decoded code tone signal with pre-established memorized codes;
• (F) generating a validating signal in response to the comparison of a predetermined number of the decoded code tone signals;
• (G) deriving from said validating signal a triggering signal;
• and
• (H) in response to said triggering signal, and before the receiver of the phone set of the called subscriber has been unhooked, supplying an indication to the calling subscriber that the pre-established code signal has been received and validated.

A method for processing coded information received through a phone line in a telephone system of the "Touch-Tone" type in which the system transmits ringing signals separated by inter-ring periods and closes a loop when a telephone call is answered, the method comprising the steps of:

• (A) normally sending from a calling subscriber signals corresponding to the phone number of a called subscriber;
• (B) when the calling subscriber receives corresponding signals indicating that ringing signals are being sent to the called subscriber in response to the establishment of a ringing circuit between the calling and the called subscribers, sending from the calling subscriber a first pre-established tone code signal during at least one of the inter-ringing periods;
• (C) blocking at the called subscriber the ringing signals received during the ringing periods while letting through a first tone code signal;
• (D) amplifying said first tone code signal;
• (E) decoding said amplified first tone code signal to obtain a first decoded signal having characters, and comparing each of said characters with corresponding characters of a first plurality of pre-established memorized codes;
• (F) generating a validating signal in response to the decoding and comparing said first tone code signal;
• (G) deriving from said validating signal a first triggering signal;
• (H) in response to said first triggering signal, sending automatically through the phone line a ringback signal to the calling apparatus as a confirmation that the first tone code signal has been received and validated;
• (I) also in response to said first triggering signal, automatically closing electrically the loop to simulate that the receiver of the called subscriber set has attended the call;
• (J) sending through the calling apparatus a second pre-established tone code signal;
• (K) decoding said second tone code signal to obtain a second decoded signal having characters, and comparing each of said characters with corresponding characters of a second plurality of pre-established memorized codes;
• (L) generating a validating signal in response to the decoding and comparing of said second tone code signal;
• (M) deriving from said validating signal a second triggering signal;
• (N) in response to said second triggering signal, sending automatically through the phone line a ring-back signal to the calling apparatus as a confirmation that the second tone code has been received and validated;
• and
• (O) in response also to said second triggering signal, and before the receiver of the phone set of the called subscriber has been unhooked, supplying an indication to the calling subscriber that the second tone code signal has been received and validated.

An apparatus for processing coded information received through a phone line forming part of a telephone system of the "Touch-Tone" type, said apparatus comprising:

• a pair of input terminals connected to the phone line for receiving said coded information,
• bandpass filtering means coupled to said pair of input terminals and having a narrow bandpass corresponding to the frequency of at least one tone code character for filtering said coded information,
• amplifying means coupled to said filtering means for amplifying said filtered coded information,
• tone decoding means coupled to said amplifying means for decoding said amplified filtered coded information to obtain a decoded output characterized by a code and a code sequence,
• code selecting means coupled to the output of said tone decoding means for selecting said code,
• sequence decoding means coupled to the output of said code selecting means for decoding said code sequence,
• an AND gate having one input coupled to the output of said sequence decoding means,
• a flip-flop having a clock input coupled to the output of said AND gate, a Q output, and an inverted Q output coupled to the other input of said AND gate,
• a transistor coupled to the Q output of said flip-flop,
• a first relay having an energizing coil coupled to the collector electrode of said transistor, said first relay having a normally open contact, a phone set being coupled to said pair of input terminals through a series-connected manually actuatable switch,
• a second relay having an energizing coil and a normally closed contact for coupling said phone set to said pair of input terminals,
• an indicating circuit coupled to said phone line input terminals through said normally open contact of said first relay,
• a ringing signal rectifying means capacitively coupled to one of said pair of input terminals through said normally closed contact of said second relay for providing a d.c. output,
• smoothing filter means connected to said rectifying means for filtering said d.c. output thereof to obtain a filter output,
• voltage stabilizing means coupled to said smoothing filter means for stabilizing said filter output to obtain a stabilized output, and
• triggering means coupled to said voltage stabilizing means and having an output coupled to an enabling input of said flip-flop, and responsive to said stabilized output for triggering said flip-flop to enable said flip-flop.

An apparatus for processing a ringing signal and coded information received through a phone line forming part of a telephone system of the "Touch-Tone" type, said apparatus comprising:

• a pair of input terminals to be connected to the phone line for receiving said coded information,
• bandpass filtering means coupled to said pair of input terminals and having a narrow bandpass corresponding to the frequency of at least one tone code character for filtering said coded information,
• amplifying means coupled to said filtering means for amplifying said filtered coded information to obtain an amplified filtered coded information having tone characters,
• tone decoding means coupled to said amplifying means for decoding the tone characters into a plurality of binary system output signals,
• code accumulating means having a plurality of inputs each coupled to said tone decoding means for accumulating a code sequence based on a sequence of said plurality of binary output signals, and issuing a code sequence output and a data output, and having a further input and a reset input,
• a timer having an enabling input coupled to said code sequence output of said code accumulating means and a timing output coupled to said further input of said code accumulating means for insuring that said code sequence is received within a predetermined time,
• comparing means having a data input coupled to said data output of said code accumulating means,
• a ringing signal input terminal,
• an inverter having an input coupled to said ringing signal input terminal and having an output,
• a NOR gate having one input coupled to the output of said inverter and having another input coupled to a first output of said comparing means and having an output coupled to said reset input of said code accumulating means,
• a random access memory having a pre-established code output coupled to a corresponding input of said comparing means,
• a counter device having an output coupled to a sequential scanning input of said random access memory,
• an oscillation generator having an output coupled to the clock input of said counter device,
• a keyboard for introducing new pre-established codes and having an output coupled to a write input of said random access memory and also coupled to an input of said counter device, said counter device having an output coupled to another input of said comparing means,
• a three-section write-read inverting switch having a first section for selectively providing an output of said code accumulating means or an output of said random access memory to a data display, a second section for selectively applying a fixed reference potential to read or write inputs of said random access memory, and a third section for selectively applying a fixed control potential input to a control input of said oscillation generator,
• a transistor coupled to a general output of said comparing means,
• a first relay having an energizing coil coupled to a collector electrode of said transistor, said first relay having also a normally open contact,
• a phone set coupled to said pair of input terminals through a series-connected manually actuable switch,
• a second relay having an energizing coil and a normally closed contact coupling said phone set to said pair of input terminals,
• an indication circuit coupled to said pair of input terminals through said normally open contact of said first relay,
• ringing signal rectifying means capacitively coupled to one of said pair of input terminals through said normally closed contact of said second relay for providing a d.c. output,
• smoothing filter means connected to said rectifying means for filtering said d.c. output,
• voltage stabilizing means coupled to said smoothing filter means for stabilizing said filtered d.c. output, and
• triggering means coupled to said voltage stabilizing means and having an output coupled to said ringing signal input terminal, and responsive to said stabilized filtered d.c. output for triggering said ringing signal input terminal when said ringing signal is received through the phone line.

An apparatus for processing coded information received through a phone line forming part of a telephone system of the "Touch-Tone" type, said apparatus comprising:

• a pair of input terminals to be connected to the phone line for receiving said coded information,
• band-pass filtering means coupled to said pair of input terminals and having a narrow pass-band corresponding to the frequency of at least one tone code character for filtering said coded information,
• amplifying means coupled to said filtering means for amplifying said filtered coded information to obtain an amplified filtered coded information having tone characters,
• tone decoding means coupled to said amplifying means for decoding the tone characters into a plurality of decimal system output signals characterized by a code and a code sequence,
• code selecting means coupled to said tone decoding means for selecting said code and having a plurality of outputs one for each tone character of pre-established codes,
• a plurality of AND gates, one for each tone character of pre-established codes, and having one of a first input coupled to a corresponding one of said plurality of outputs of said code selecting means, and having a second input,
• sequence decoding means for decoding the code sequence, and having a plurality of inputs, one for each tone character of pre-established codes, and each being coupled to an output of a corresponding one of said plurality of AND gates,
• a flip-flop having a clock input coupled to said sequence decoding means,
• a further AND gate having a first input coupled to the output of said flip-flop and second and third inputs,
• an oscillation generator of very low frequency having an output coupled to said second input of said further AND gate,
• a timer having a triggering input selectively connectable to one of said plurality of outputs of said tone decoding means and responsive thereto for issuing a timer output corresponding to a desired time for transfer of said selected code via said plurality of AND gates to said sequence decoding means,
• a monostable device coupled to the output of said timer, and having an output coupled in parallel to said second input of said plurality of AND gates, to the enabling input of said flip-flop, and to said third input of said further AND gate,
• a first transistor coupled to said output of the monostable device,
• a first relay having an energizing coil coupled to a collector electrode of said first transistor and having a normally open contact connected to the pair of input terminals through a resistor simulating electrically the resistance of a conventional phone set, and having also a second normally open contact connected in parallel with said amplifying means through a gain reducing resistor,
• a second monostable device having a triggering input capacitively coupled to said collector electrode of the transistor,
• a ring-back oscillation generator coupled to the output of said second monostable device, said ring-back oscillation generator having an output coupled to one of said pair of input terminals for providing a ring-back signal thereto,
• a phone set coupled to said pair of input terminals through a series-connected manually actuable switch,
• a second relay having an energizing coil and a normally closed contact connecting said phone set to said pair of input terminals, and
• an indicating device coupled to the output of said AND gate, said normally closed contact of said second relay being connected in series with the pair of input terminals.

A method for validating a telephone call between a calling party and a called party using a predesignated code in a telephone system of the Touch-Tone type, comprising the steps of:

• (A) transmitting, from the calling party, signals corresponding to the phone number of the called party;
• (B) establishing a ringing circuit to the called party in response to the signals corresponding to the phone number of the called party;
• (C) transmitting consecutive ringing signals, separated by corresponding inter-ring periods, over the ringing circuit to the called party;
• (D) transmitting, from the calling party during said corresponding inter-ring periods, at least one code signal;
• and
• (E) comparing said at least one code signal with said predetermined code, and in response to a match therebetween, validating said telephone call in response to transmission of said at least one code signal.

A system for validating a telephone call between a calling party and a called party using a predesignated code for use in a telephone system of the Touch-Tone type, comprising:

• first transmitting means for transmitting, from the calling party, signals corresponding to the phone number of the called party;
• ringing circuit means responsive to the signals corresponding to the phone number of the called party for establishing a ringing circuit to the called party;
• second transmitting means for transmitting consecutive ringing signals, separated by corresponding inter-ring periods, over the ringing circuit to the called party;
• said first transmitting means adapted to transmit, from the calling party during said corresponding inter-ring periods, at least one code signal;
• and
• comparing means for comparing said at least one code signal to said predesignated code to validate said telephone call in response to transmission of a code signal corresponding to said predesignated code.