US PATENT SUBCLASS 379 / 156
MULTI-LINE OR KEY SUBSTATION SYSTEM WITH SELECTIVE SWITCHING AND CENTRAL SWITCHING OFFICE CONNECTION

Current as of: June, 1999
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379 /   HD   TELEPHONIC COMMUNICATIONS

156MULTI-LINE OR KEY SUBSTATION SYSTEM WITH SELECTIVE SWITCHING AND CENTRAL SWITCHING OFFICE CONNECTION {7}
157  DF  .~> With special service {1}
159  DF  .~> With intercom system {1}
161  DF  .~> With exclusion or priority feature (e.g., lockout or privacy)
162  DF  .~> Detail of hold circuitry {1}
164  DF  .~> Line status indication or call alerting
165  DF  .~> Switching or supervision feature (e.g., common control, digital)
166  DF  .~> Detail of line circuit or line card

DEFINITION

Classification: 379/156

MULTI-LINE OR KEY SUBSTATION SYSTEM WITH SELECTIVE SWITCHING AND CENTRAL SWITCHING OFFICE CONNECTION:

(under the class definition) Subject matter including circuitry for allowing a subscriber terminal to be selectively connected to one of a plurality of lines, at least one of which is a public telephone line.

(1) Note. Each public telephone line is associated with a unique director number.

(2) Note. A PBX is a system connected to one of a plurality of shared usage lines (trunks) as opposed to lines associated with individual directory numbers; however, a key system may be associated with a PBX system.