Patent CA-2061616-A1 (CA)
Title: Door answering interconnect system utilising either an inside intercom or radio-communication system or a public or private subscriber telephone network, interconnected to an outside or entrance-hall intercom system, including  video retrans ission possibilities
Inventor: ROBERT VIEN JOSEPH G N
IPC: H04B7/24
Filed: 1992-02-20
Abstract: A  B  S  T  R  A  C  T       A discreet communications interconnect system between the public subscriber telephone network, or an interior intercom, or a  private  or  commercial  radio-communication  system,  and any intercom or speaker phone system located at the door or in the entrance-hall of a residence or of a commercial building. When the building occupant is on the premises, he can either answer directly at the door or through the inside intercom.  If the occupant is absent, the said link, after being set to OPTION I or OPTION 2 stand-by status   by  the building occupant  before  leaving  the building, will automatically be switched on every time a visitor will ring the outside bell. When a visitor does ring the outside bell,   ...OPTION  1.  an  easely recognizable  tone-signal  is automatically transmitted through the radio-communication system. The answering party , with his first transmission on his radio, automatically establishes the audio path to the outside speaker with the visitor. The conversation will then occur back and forth using either simplex VOX, simplex sampling or half-duplex modes technology, as programed by the answering party, as if through a normal  intercom system. When the conversation is over and the visitor leaves,  the audio path between the radio-communication system and the outside speaker is automatically cut after one to 5 minutes of radio silence from the answering party. ...OPTION 2. An automatic dial-up operation is initiated via a public or private subscriber telephone network to a unique telephone number pre-programmed by the building occupant before leaving the premises. The pre-programmed phone number could be a cellular phone or any other phone number of a location where the individual expects to be present within a short period of time or the number of another trusted person who would know how to handle the call properly. When his phone rings, the answering party will hear a caracteristic "DING-DONG-like" tone that will be transmitted on the phone line by the said communications interconnect control-board, alerting the answering party that someone is at the door. Depending on how the system was programed, the answering party will either automatically have audio path to the outside intercom at the door or he will then transmit a "*" using any "touch-Tone" telephone key-pad, thereby allowing audio from the answering party to be heard by the visiting party.  From  that  moment  on,  a  normal  phone-like  two-way communication will be established between the answering party and the visiting party, through the subscriber telephone network, via the outside intercom. The control-board will be designded so that DTMF (Touch Tones) will never be heard by the visitor,  thereby making him beleive that he is talking to someone inside and not to someone on the phone. Interesting security feature, isn't it? Since the answering party is not present on the premises, he would then find some excuse as to why he cannot actualy go to the door and would then suggest to the visitor that they could meet at some other time or talk on the phone later. The outside intercom audio could be temporarily muted if needed by the answering party through the use of other DTMF "Touch-tone" codes. Once the conversation is completed,  the answering party  then  transmits the "#"  on his "Touch-Tone" key-pad, thereby inducing hang-up of the phone line on the side of  the visitor.  If the answering party omits to transmit the "#", the line will be automatically hung-up by the control-board after a short while. The control-board on location will be remotely programmable through the phone line as long as the phone line is not in "call-forwarding"   mode to another phone