 If the operator could not get through by dialing the number, she could call the inward operator in the destination city, and ask her to try the number, or to test a line to see if it was busy or out of order.Cord switchboards used for these purposes were replaced in the 1970s and 1980s by TSPS and similar systems, which greatly reduced operator involvement in calls.The customer would, instead of simply dialing "0" for the operator, dial 0+NPA+7digits, after which an operator would answer and provide the desired service (coin collection, obtaining acceptance on a collect call, etc.