Automatic calling number identification

Claim 1

IN A TELEPHONE SYSTEM, A LOCAL OFFICE, CALLING LINE CIRCUITS, IDENTIFYING EQUIPMENT AT SAID LOCAL OFFICE INCLUDING MEANS FOR REGISTERING THE DIGITS OF A CALLING LINE DESIGNATION, A TANDEM OFFICE, CHARGE RECORDING MEANS AT SAID TANDEM OFFICE, AN OPERATOR POSITION AT SAID TANDEM OFFICE, MEANS TO CONNECT SAID LINE IDENTIFYING EQUIPMENT WITH A CALLING LINE CIRCUIT TO REGISTER THE DESIGNATION OF SAID LINE, MEANS UNDER THE CONTROL OF SAID REGISTERING MEANS TO TRANSMIT AN INFORMATION DIGIT FOLLOWED BY THE DIGITS OF SAID CALLING LINE DESIGNATION TO SAID CHARGE RECORDING MEANS, MEANS EFFECTIVE IF SAID LINE IDENTIFYING EQUIPMENT CANNOT IDENTIFY THE CALLING LINE DESIGNATION TO TRANSMIT A DIFFERENT INFORMATION DIGIT TO SAID TANDEM OFFICE, AND MEANS RESPONSIVE TO SAID DIFFERENT INFORMATION DIGIT TO CONNECT SAID OPERATOR POSITION WITH SAID CALLING LINE AND TO PLACE SAID CHARGE RECORDING MEANS UNDER THE CONTROL OF SAID OPERATOR POSITION.