Telephonic communications – Plural exchange network or interconnection – Connection call model
Patent
1989-05-24
1990-07-24
Dwyer, James L.
Telephonic communications
Plural exchange network or interconnection
Connection call model
379279, H04M 714
Patent
active
049439995
ABSTRACT:
A switching arrangement is disclosed in which connections are advanced between lines and trunks of a first telecommunication switching system via a central switch of the first telecommunication switching system and, when the central switch is unavailable, via a first trunk from the first telecommunication switching system to a second telecommunication system and a connection through the second telecommunication switching system to a second trunk back to the first telecommunication switching system. The first switching system comprises a first and second unit connected by the first and second trunks, respectively, to the second switching system. A control unit in the first switch unit determines when the central switch is unavailable and in response to a dialed request for connection to a line or trunk at the second switch unit, advances the connection via the first trunk to the second switch system. The second switching system, in response to signaling information from the first switch unit completes a connection to the second switch unit via the second trunk. Advantageously, the first and second trunks to the second switching system are used for end office calls to and from the second switching system when the central connection arrangment of the first switching system is available to complete calls at the first switching system and the first and second trunks are used for the connection of sources and destinations at the first switching system when the central connection arrangement is unavailable. The first and second trunks are continuously provided trunk services such as scanning and signaling, which normally enables the advancement of end office connections to lines and trunks of the second switching system.
REFERENCES:
patent: 3217109 (1965-11-01), Abert
patent: 4486626 (1984-12-01), Kohler
patent: 4583218 (1986-04-01), Ardon et al.
patent: 4755995 (1988-07-01), Anderson et al.
patent: 4811388 (1989-03-01), Westerhof et al.
patent: 4853957 (1989-08-01), Seeger et al.
G. Zorpette, "Keeping the Phone Lines Open", IEEE Spectrum, vol. 26, No. 6, Jun. 1989, pp. 32-66.
AT&T Bell Laboratories
Dwyer James L.
Samples Kenneth H.
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