Multiplex communications – Wide area network – Packet switching
Patent
1983-06-27
1985-11-05
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
370104, H04J 312
Patent
active
045518351
ABSTRACT:
A system is disclosed to provide X.21 in-band call establishment signaling in the data path of a data communication system by utilizing a data port, digital switch and telephone signaling call processor in a satellite communications controller. The system includes an X.21 signaling protocol between a DTE and the satellite communications controller on the terrestrial side and allows self-switched digital data port functions in lieu of associated voice port and line functions as practiced in the prior art. An important aspect is that the signaling rate is the same as the line data rate. The data port goes through three generalized states during a normal call process. The first general state is idle, the second general state is the signaling state and the third general state is the data transfer state. At the start of the signaling state, the E input to the call processor is activated for the appropriate port. Call establishment signals are then processed through the digital switch and an X.21 adapter to the system's control processor. In the third data transfer state, the call establishment signaling has been completed and all data bits go through the digital switch and are transmitted to the digital interface. At the end of the call the data port goes back to the first, idle state.
The significant overall feature of the system is the provision for X.21 in-band signaling on the terrestrial side of the satellite communications controller so that a digital data port can accept X.21 in-band call processing type signals. The digital data port detects the call processing type signals with the X.21 protocol and passes them on to the X.21 adapter in the satellite communications controller.
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Bensadon Joseph M.
Brickman Norman F.
Hoel John E.
International Business Machines - Corporation
Olms Douglas W.
Scutch III Frank M.
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