Communications system and method

This invention relates to telecommunications systems and in particular to an apparatus and method for selecting voice encoding algorithms in such systems. In a communications system in which narrow band, e.g. voice, channels are carried in packet form over an asynchronous network, each channel is encoded to reduce its bit rate so as to reduce demands on band width. The encoding of each channel is effected via an algorithm selected from a group of algorithms associated with that channel. The algorithms forming the group are identified to a receiver station performing a decoding function via information provided in each packet header. The particular algorithm currently in use is determined implicitly from the packet length or from a combination of the packet length and a discriminator field provided in the packet header.