An integrated voice and packet data telecommunications system has at least one dual mode channel. The system comprises a plurality of transceivers, at least one transceiver being operable to transmit and receive voice traffic on the dual mode channel, and at least one transceiver being operable to transmit and receive packet data traffic on the dual mode channel. The system further comprises a controller for controlling the transceivers so as to allocate the dual mode channel either to voice communications or to packet data communications. The controller responds to changing demand for voice channels and packet data channels by changing dynamically the allocation of the dual mode channel. The system is particularly useful for providing Cellular Digital Packet Data (CDPD) services.

A cellular packet data arrangement includes an interface unit (NIU) to a packet data network and link interface units (LIUs) each providing a channel to a respective radio transceivers for communicating data packets with mobile terminals each having an individual identifier (TEI). Each LIU stores the TEI, channel number, and protocol data for communications with each mobile terminal handled by the LIU. In response to a first LIU receiving a communication from a mobile terminal whose communications have previously been on a channel handled by a second LIU, this is identified from the mobile terminal's TEI not being stored in the first LIU and being stored in the NIU in respect of the second LIU, and the protocol data for the mobile terminal is transferred from the second to the first LIU. To avoid a possible error condition, the first LIU can suppress a reply to the communication from the mobile terminal until this is resent.