A voice processing complex has a plurality of host machines, each host machine supporting one or more voice applications, at least one host in the complex including telephony hardware for providing access to a plurality of telephone lines. Such a host provides telephony functions to the complex. This is achieved by maintaining a mapping of voice applications to telephone lines, and creating a call object in response to an incoming call on one of the lines. It is then determined which voice application to associate with the incoming call on the basis of this mapping, and an identifier to the call object is then passed to the determined voice application. Thereafter the call object is responsive to requests from this voice application for providing telephony functions for the call. This includes receiving a media object from the voice processing application which represents desired output over a telephone line. This media object is then processed into a plurality of output components in accordance with one or more presentation criteria, and these components are then output over the telephone line.