Mobile communications system and a transcoder unit

A mobile communication system which comprises:

• a base station having a data transmission connection to a mobile services switching centre through a transcoder unit, wherein the base station transmits and, correspondingly, receives speech parameters over a radio connection from a mobile station located within the base station's radio coverage area,
• the transcoder unit decodes the speech parameters it has received from the base station to speech signals to be transmitted to the mobile services switching centre and, correspondingly, for encoding the speech signals it has received from the mobile services switching centre to speech parameters to be transmitted to the base station, and
• a circuit-switched data transmission connection for the base station and the transcoder unit to communicate with one another, on which data transmission connection the speech parameters are transmitted by TRAU frames, wherein
• the data transmission connection between the base station and the transcoder unit is partly composed of a packet-switched data transmission connection, and
• a converter is arranged on the data transmission connection between the base station and the transcoder unit, the converter converting a packet received from said packet-switched data transmission connection into a TRAU frame to be transmitted over the circuit-switched connection, said conversion including at least the addition of synchronization bits to the TRAU frame.

A transcoder unit comprising:

• a transcoder which includes:
• decoding means for decoding speech parameters the transcoder unit has received from a first data transmission connection and for forwarding them as speech signals over a second data transmission connection, and
• encoding means for encoding speech signals the transcoder unit has received from the second data transmission connection and forwarding them as speech parameters over the first data transmission connection, wherein
• the first data transmission connection is a packet-switched data transmission connection, wherein the transcoder unit is connected to the first data transmission connection through a converter means, the converter means comprising means for converting a packet received from the packet-switched data transmission connection into a TRAU frame, said conversion including at least the addition of synchronization bits to the TRAU frame, and for transmitting said TRAU frame to the transcoder of the transcoder unit over a circuit-switched connection.