TDD/TTY-digital access

• US 6,381,472 B1
• Filed: 12/21/1998
• Issued: 04/30/2002
• Est. Priority Date: 12/21/1998
• Status: Expired due to Term

• Current Assignee: Bell Atlantic Mobile Systems LLC (Verizon Communications Inc.)
• Original Assignee: Bell Atlantic Mobile Inc (Verizon Communications Inc.)
• Inventors: LaMedica, Louis Jr., Whritenour, Lee J.
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/217,248
• Time in Patent Office: 1,226 Days
• Field of Search: 455/557, 455/556, 455/560, 455/507, 379/52, 379/93.17, 379/93.18
• US Class Current: 455/560
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 88/14 Backbone network devices
• CPC Class Codes: H04W 88/184 Messaging devices, e.g. message centre
• CPC Class Codes: H04W 92/18 between terminal devices

Abstract

Digital wireless telephone equipment is adapted to support existing data services for the hearing or speech impaired. The data devices use existing analog tone transmission protocols. The digital telephone equipment provides protocol conversions between the standard tone signals used by TDD/TTY devices or the like and data messages in the form of a standard data protocol utilized within the air-link of the digital wireless telephone system. In either direction, each tone generated by the data device is detected. Upon detection of one or more tones, a protocol converter generates a data message signifying the bit(s) represented by the tone signals in a format used by the air-link protocol. The converter supplies the data message to the appropriate digital radio transceiver. The transceiver inserts the message into the data stream with any other information for the pertinent subscriber, such as vocoded audio information. The transceiver sends the combined data stream over the air-link. Another unit receiving the transmission reverses the process to recover the messages and generate corresponding tone signals. The tone signals can be mixed in with any received audio information, enabling a person to send and/or receive verbal communications along with the textual communications.

Claims

1. A mobile switching center, comprising:

a digital switch for establishing selective connections of a port to circuits going to digital wireless base stations;

demultiplexer means, coupled to the port of the digital switch, for separating digital messages representing predetermined tone signals compatible with a data device for an impaired user from vocoded speech samples in a data stream received from one of the wireless base stations;

a vocoder coupled to the demultiplexer means for digitally decoding the vocoded speech samples into representations of analog audio signals;

a decoder, coupled the demultiplexer means, for decoding the digital messages to identify the predetermined tones;

a generator responsive to the decoder, for producing representations of the predetermined tones; and

a combiner, coupled to the vocoder and the generator, for combining the representations of analog audio signals and the representations of the predetermined tones into a signal stream for transmission over a telephone network.

2. A mobile switching center as in claim 1, wherein the generator generates representations of frequency shift key modulation tones.

3. A mobile switching center as in claim 1, further comprising:

a tone detector for detecting representations of predetermined tone signals for the data device for the impaired user; and

an encoder, coupled to the tone detector, for generating digital data messages corresponding to the detected tone signals for transmission through the one wireless base station.

4. An apparatus as in claim 3, wherein the tone detector detects representations of frequency shift key tone signals.