| 摘要 |
The present invention relates to intercom systems, and more particularly to an intercom system where one station is located on the outside of a dwelling adjacent to an entry door and all other stations are the existing telephone sets which prior to embodying the invention where in the sole use of being part of the telephone company network. Door intercom systems have become increasingly popular as a form of security and convience when responding to the activitation of a "door bell" While such systems operate very well , a significant detracting factor in their use is the installation costs and number of stations in the dwelling. In this invention the wiring currently in use by the door bell button is re-assigned to the intercom as are the telephone sets and their associated wiring in the dwelling.
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