Text transmission using DTMF signalling
First Claim
1. A method comprising the steps of:
- transmitting from a switching unit a first signal, said first signal being selected from the group consisting of a first ring signal and a voltage polarity reversal signal;
receiving said first signal at a receiver unit;
transmitting from said switching unit a start multifrequency signal, said start multifrequency signal being indicative of a start of a text transmission;
receiving said start multifrequency signal at said receiver unit;
transmitting a second multifrequency signal from said switching unit;
receiving said second multifrequency signal at said receiver unit;
transmitting a third multifrequency signal from said switching unit;
receiving said third multifrequency signal at said receiver unit, wherein said second and third multifrequency signals contain information indicative of a text character;
transmitting an end multifrequency signal from said switching unit, said end multifrequency signal being indicative of an end of said text transmission;
receiving said end multifrequency signal at said receiver unit; and
thentransmitting from said switching unit a second signal, said second signal being a ring signal; and
receiving said second signal at said receiver unit.
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0 Petitions
Accused Products
Abstract
A method and system for transmitting text information using multifrequency signals is provided. A switching center transmits a first multifrequency signal indicating the start of a text transmission. A receiver unit receives the first multifrequency signal and prepares to receive text information. The switching center transmits to the receiver unit a second and third multifrequency signals after the first multifrequency signal. The second and third multifrequency signals contain information corresponding to a text character. The receiver unit receives the second and third multifrequency signals and determines the text character transmitted. The switching center transmits a fourth multifrequency signal to the receiver unit indicating the end of the text transmission.
37 Citations
27 Claims
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1. A method comprising the steps of:
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transmitting from a switching unit a first signal, said first signal being selected from the group consisting of a first ring signal and a voltage polarity reversal signal; receiving said first signal at a receiver unit; transmitting from said switching unit a start multifrequency signal, said start multifrequency signal being indicative of a start of a text transmission; receiving said start multifrequency signal at said receiver unit; transmitting a second multifrequency signal from said switching unit; receiving said second multifrequency signal at said receiver unit; transmitting a third multifrequency signal from said switching unit; receiving said third multifrequency signal at said receiver unit, wherein said second and third multifrequency signals contain information indicative of a text character; transmitting an end multifrequency signal from said switching unit, said end multifrequency signal being indicative of an end of said text transmission; receiving said end multifrequency signal at said receiver unit; and
thentransmitting from said switching unit a second signal, said second signal being a ring signal; and receiving said second signal at said receiver unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 26)
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8. A system comprising:
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a switching unit capable of providing a first signal and a second signal, said first signal being selected from the group consisting of a first ring signal and a voltage polarity reversal signal, said second signal being a ring signal, said switching unit including a signal generator capable of providing a start multifrequency signal after said first signal is provided, at least a second multifrequency signal and a third multifrequency signal, and an end multifrequency signal before said second signal is provided; and a receiver unit capable of receiving said first signal, said start multifrequency signal, said at least said second and third multifrequency signals, said end multifrequency signal and said second signal, wherein; said start multifrequency signal is indicative of a start of a text transmission; said at least said second and third multifrequency signals contain information indicative of at least one text character; and said end multifrequency signal is indicative of an end of said text transmission. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A device for receiving DTMF signals containing text data transmitted by a switching unit over a transmission channel, comprising:
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a transmission channel interface coupled to said transmission channel; a DTMF receiver coupled to said transmission channel interface, said DTMF receiver being capable of receiving said DTMF signals; and a controller coupled to said DTMF receiver, said controller being capable of decoding received DTMF signals into text data; wherein said DTMF receiver includes; structure for receiving a start signal after transmission of a first signal from said switching unit and prior to receipt of said DTMF signals containing said text data, said first signal being selected from the group consisting of a first ring signal and a voltage polarity reversal signal; and structure for receiving an end signal following receipt of said DTMF signals containing said text data and prior to transmission of a second signal from said switching unit, said second signal being a ring signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A method comprising the steps of:
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transmitting from a switching unit a first signal, said first signal being selected from the group consisting of a first ring signal and a voltage polarity reversal signal; receiving said first signal at a receiving unit; transmitting from said switching unit a start multifrequency signal, said start multifrequency signal being indicative of a start of a text transmission; receiving said start multifrequency signal at said receiver unit; transmitting a first selected number of multifrequency signals from said switching unit in sequence; receiving said first selected number of multifrequency signals at said receiver unit, wherein said first selected number of multifrequency signals contain information indicative of a second selected number of text characters; transmitting an end multifrequency signal from said switching unit, said end multifrequency signal being indicative of an end of said text transmission; receiving said end multifrequency signal at said receiver unit; and
thentransmitting from said switching unit a second signal, said second signal being a ring signal; and receiving said second signal at said receiver unit. - View Dependent Claims (25, 27)
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Specification