Automatic telephone system having restricted service means

Claim 1

AN AUTOMATIC TELEPHONE SYSTEM COMPRISING A PRIVATE BRANCH EXCHANGE HAVING A PLURALITY OF SUBSCRIBER TELEPHONES; A PLURALITY OF TRUNK MEANS FOR CONNECTING SAID TELEPHONES TO A CENTRAL OFFICE; SELECTOR MEANS FOR SELECTIVELY CONNECTING ONE OF SAID TELEPHONES TO ONE OF SAID TRUNKS IN RESPONSE TO A PREDETERMINED DIAL SIGNAL SENT BY SAID ONE OF SAID TELEPHONES; BLOCKING MEANS IN SAID TRUNK MEANS FOR BLOCKING CALLS TO SAID CENTRAL OFFICE UPON ENERGIZATION OF SAID BLOCKING MEANS; A REGISTER MEANS FOR DETECTING DIALING SIGNALS; EACH SAID TRUNK MEANS HAVING AN ASSOCIATED CONTROL MEANS CONNECTED THERETO FOR CONNECTING SAID REGISTER TO SAID ASSOCIATED TRUNK IN RESPONSE TO SAID ASSOCIATED TRUNK SEIZING SAID CENTRAL OFFICE; MEANS IN SAID CONTROL MEANS FOR TRANSMITTING DIALING SIGNALS FROM SAID ASSOCIATED TRUNK MEANS TO SAID REGISTER MEANS; SAID CONTROL MEANS OBSERVING THE DIALING SIGNALS ON EVERY ATTEMPT TO SEIZE SAID CENTRAL OFFICE; FIRST MEANS IN SAID REGISTER MEANS FOR DISCONNECTING SAID REGISTER MEANS FROM SAID TRUNK MEANS UPON DETECTING A PREDETERMINED NUMBER OF SAID DIAL SIGNALS; AND SECOND MEANS IN SAID REGISTER MEANS CONNECTED TO SAID TRUNK MEANS FOR ENERGIZING SAID BLOCKING MEANS UPON DETECTING A PREDETERMINED DIALING SIGNAL.