A voice synthesis system for interactive voice services comprises a voice server connected to a packet network dispensing a voice service to a user terminal by executing a service file associated with the voice service. An HTTP client in the voice server transmits a request containing a text to be synthesized during execution of the service file. The service file includes an address designating a resource in a voice synthesis server connected to the packet network and a command responsive to the audio format for commanding the transmitting of the request to the voice synthesis server. An HTTP server in the voice synthesis server transmits to the voice server an audio response including the text that has been synthesized by the voice synthesis server independently of the voice server.