Abstract: Methods and apparatus for enabling simultaneous transmission of voice and data signals over a single subscriber line. Signals are time division multiplexed preferably using an ISDN access format such as the Basic Access or Primary Rate formats, but are treated separately at the exchange. Subscriber equipment combines signals from local computer and telephone devices for separation at corresponding exchange equipment. Similarly the exchange equipment combines signals from one or more packet networks and the public telephone network for separation at the subscriber equipment. Data signals are therefore passed by the exchange directly to or from a packet switched network while voice signals are passed directly to or from a telephone switched network. Channels available over the subscriber line are dynamically allocated with telephone signals generally taking preference over data signals.