A distributed voice processing system comprises two or more voice processing machines (50A, 50B), connected by an isochronous network. In the preferred embodiment this network comprises an ATM switch (80) and appropriate ATM links (82A, 82B). Each of the voice processing machines includes telephone line interface units (52) connected to the telephone network (5) via respective telephony channels (15), a TDM bus (54), voice resources (55) (such as voice recognition, voice response functionality, etc.), and an ATM adapter (58) to allow communications over the ATM network. In operation, a call may be received at the line interface unit at a first voice processing machine, and placed onto a TDM bus at that machine. The call is then taken off the TDM bus by the ATM adapter, and routed over the ATM network to the ATM adapter at a second machine, which places the call on the TDM bus at this second machine. The call is then processed by a voice resource at this second machine, which has access to the TDM bus, thereby allowing a call to be handled by a line interface unit at a first voice processing machine and a voice resource at a second voice processing machine.