George W Clement

US Patent:

41139860, Sep 12, 1978

Filed:

Oct 21, 1977

Appl. No.:

5/844377

Inventors:

George Frederick Clement - Naperville IL
Bruno Raymond Sniegowski - Westerville OH

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ
Western Electric Company - New York NY

International Classification:

H04M 1100

US Classification:

179 2A

Abstract:

Circuitry is disclosed for the automatic dial-up of an apartment telephone from a lobby telephone to provide voice communication therebetween via a central switching office and for controlling the establishment of a switched signaling path through a switching network independent of the central office and then the unlocking of the lobby door over that switched path. The circuitry includes a trunk circuit for connecting the lobby telephone set to the central office and service circuits for detecting and processing call on/off-hook and ring signals as well as lobby door lock release signals from the called apartment. Distinctive tone bursts are applied by a service circuit through the switched path to notify the called apartment dweller of a lobby originated call.