Abstract: The current invention provides apparatus for relieving congestion associated with interfacing voice-band data, and broad-band data, with a network such as the public switched telephone network (PSTN). A hierarchical system for converting digital transmissions on a network between a first protocol and a second protocol is disclosed. The transmissions are generated by data terminals communicating in a third protocol with the network. The hierarchical system includes: interface units, a local processor, a first remote processor and a first controller. The interface units are each coupled to corresponding ones of the data terminals and each signal a call session with the corresponding data terminal. The interface units convert the transmissions from the data terminal in the third protocol to the second protocol. The local processor is switchably coupled to the interface unit and communicates with the network. The local processor converts digital transmissions from the second protocol to the first protocol.

Abstract: The current invention provides methods for relieving congestion associated with interfacing multiple types of subscriber link traffic, i.e. voice, voice-band data, and broad-band data, with a network such as the public switched telephone network (PSTN). In an embodiment of the invention waste of modem resources is diminished by reducing the magnitude of the transmission parameters between a data terminal and modem resources during intervals of reduced data flow. This frees scarce modem resources for other sessions. In another embodiment of the invention the time required to initiate session setup is reduced. This reduces the time devoted by modem facilities to call setup at the start of session, or after an idle period.