Patent ID: 7382752
Filing Date: 2008-06-03
Classification: H04B

Abstract:
1. Apparatus for a mobile node that communicates by way of a radio link, the mobile node comprising a text telephony (TTY) device through which a user enters TTY data and a cellular mobile station operable to communicate pursuant to the radio telephonic communication system, the mobile node operable at least to send data signals representative of TTY data to a destination comprising a TTY station, said apparatus comprising: a cellular text modem (CTM) modulator selectably adapted to receive the TTY data that is to be communicated, said CTM modulator for modulating the TTY data pursuant to a CTM modulation scheme for communication to the destination by way of a first connection; a TTY modulator selectably adapted to receive the TTY data that is to be communicated, said TTY modulator for modulating the TTY data pursuant to a TTY modulation scheme for communication to the destination by way of a second connection; a detector embodied at the mobile node, said detector at least for detecting failure of formation of the first connection, absence of the formation of which prevents communication of the signals representative of the TTY data when modulated pursuant to the CTM modulation scheme by said CTM modulator; and a selector adapted to receive indications of detection made by said detector, said selector for selecting to form the second connection with the destination and to modulate the signals representative of the TTY data pursuant to the TTY modulation scheme by said TTY modulator, thereby to permit communication of the signals representative of the TTY data, modulated pursuant to the TTY modulation scheme, by way of the second connection; wherein the mobile node is initially operable to attempt to send the signals, representative of the TTY data entered through the TTY device by the user, by way of the first connection, said detector detecting failure of the formation of the first connection responsive to detection of a failed negotiation to form the first connection.