Call data monitoring for electromechanical telephone switching systems

摘要

In order to provide call data monitoring for an Automatic Electric step-by-step switching system, the identification of the line number of a calling subscriber line in a group of subscriber lines is accomplished by identifying which of the line finders for that group has been selected by detecting a marked location in the selected line finder corresponding to the calling subscriber line and by detecting which of the common control relays for the group has selected and controlled the line finder. Identification of the line finder, the marked location and the common control relays are converted into the line number of the calling subscriber and stored as a first item in a call data record. The dialed telephone number of the called subscriber is determined and is stored as a second item in the call data record. The start time of the call is determined and is stored as a third item in the call data record. The duration of the call is determined and is stored as a fourth item in the call data record. Modifications necessary to provide call data monitoring for other types of step-by-step switching systems and for all-relay switching systems are also set forth.