Abstract: A transcoder is described for performing transcoding operations, that is to say coding and decoding operations on voice data arranged over a plurality of voice data channels. It comprises a first interface (10) for inputting and outputting coded voice data, a second interface (11) for inputting and outputting decoded voice data; at least one transcoder processor (101) for performing transcoding operations on voice data arranged over at least two voice data channels; and an input/output processor (100) coupled to the first and second interfaces and the at least one transcoder processor for controlling the flow of data between the first and second interfaces and the at least one transcoder processor. The input/output processors controls the at least one transcoder processor to perform transcoding operations on a selected channel at a given time. The invention is particularly applicable to transcoding between CEPT standard voice data and GSM standard voice data.