An interface architecture and protocol are provided for transferring messages between a plurality of devices. The architecture provides the capability to generate a plurality of service messages according to a single message format, and to transfer the service messages between a plurality of control points or service entities according to an efficient multiplexing protocol. The control points can be software applications or device drivers running on a terminal equipment device, and the service entities can be communication services such as network access services or device management services running on an attached data communication device such as a modem or a cellular phone.