A method of repeating a non-voice signal such as a dual tone, multiple
frequency (DTMF) signal, by inserting a delay sequence of data values into
an output data sequence of data values, a portion of the output data
sequence following the delay sequence being the same as a corresponding
portion of an input sequence of decoded data obtained from a low bit-rate
speech decoder. The input sequence has at least one distorted non-voice
sequence. The method provides for inserting a substantially undistorted
non-voice sequence into the output sequence, the undistorted sequence
being at least of substantially the same length as the distorted sequence,
a portion of the output sequence following the undistorted sequence being
the same as a corresponding portion of the input sequence, and the output
sequence being substantially free of the distorted non-voice signal.
