TDD/TTY-digital access

摘要

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.