专利名称：AUTOMATIC SECURITY COMMUNICATIONS
SYSTEM
发明人：PUIG A,US申请号：US37002973申请日：19730614公开号：US3826875A公开日：19740730
摘要：An automatic communication system adapted to provide security
communications within an apartment building is provided to include a plurality of timedelay circuits to automatically discontinue the ringing of an unanswered phone and toterminate the call when the receiver is not hung up.
申请人：PUIG A,US
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