METHOD OF CLEANING TELEPHONE NUMBER LIST

摘要

PROBLEM TO BE SOLVED: To provide a mechanism for enquiring a telephone number actually used in a telephone line network by using a computer and a mechanism for cleaning an existing telephone number list based on the enquiry results while leaving the network off-line instead of cleaning a telephone number list by actually calling the network. SOLUTION: All area codes and city codes included in an area to be enquired are obtained according to public information and these codes are made into a table as codes to be enquired in advance. Telephone numbers to be enquired include all combinations of all the codes to be enquired and four-digit numbers which can be subscriber's numbers. The telephone numbers to be enquired are successively called by a personal computer connected to ISDN and responses are checked.