Web service support for a multimodal client processing a multimodal application, the multimodal client providing an execution environment for the application and operating on a multimodal device supporting multiple modes of user interaction including a voice mode and one or more non-voice modes, the application stored on an application server, includes: receiving, by the server, an application request from the client that specifies the application and device characteristics; determining, by a multimodal adapter of the server, modality requirements for the application; selecting, by the adapter, a modality web service in dependence upon the modality requirements and the characteristics for the device; determining, by the adapter, whether the device supports VoIP in dependence upon the characteristics; providing, by the server, the application to the client; and providing, by the adapter to the client in dependence upon whether the device supports VoIP, access to the modality web service for processing the application.