Method and apparatuses for controlling encoding of a dataflow

A method of controlling encoding of a data flow to be transmitted in accordance with at least one of a plurality of encoding schemes over a channel of a bearer established between a first network node and a second network node of a wireless communications system. A memory is provided having a plurality of entries, each entry being operable to store encoding context information relating to an encoding scheme being applied to a data flow being transmitted by the first network node. A reserved area of the memory is provided having a plurality of reserved entries operable to store encoding context information relating to a subset of the plurality of encoding schemes. On receipt of a request to support transmission of a new data flow, it is determined whether entries currently unused for storing encoding context information are only available in the reserved area and, if so, a preservation state is entered where the new data flow is encoded with at least one of the subset of the plurality of encoding schemes.