lly increased because access charges were levied without regard to the time of day or the actual price or intercity distance of the call. Predivestiture toll rate matrices, with time-of-day and mileage-based pricing, eventually gave way to "postalized" long distance rates. Selecting Equal Access Carriers The MFJ itself was designed to break the back of AT&T's long distance monop- oly. In addition to spinning off the RBOCs, it called for the RBOCs and GTE to offer subscribers a choice of primary interexchange carrier (PIC) as part of the equal access process. As exchanges were upgraded to equal access, which occurred in most central offices during the mid-1980s, subscribers were given a ballot on which to select their PIC. A customer would always be assigned to the PIC it selected. But if a customer did not return the ballot, it was randomly assigned to a carrier; each carrier's share of these customers was proportionate to its share of the returned ballots. 800-Number Competition Divestiture and equal access did not create competition for one very important sector of the long distance industry, reverse-toll dialing (800 numbers). This remained AT&T's monopoly for several years. The first 800-number competi- tion was limited, based on assigning specific NXX codes to interexchange carri- ers; for instance, 800-950 was assigned to MCI. A company thus could not move its existing 800 service to a different carrier, but it could get a new number from a competitor. During the late 1980s, the RBOCs implemented the first phase of intelli- gent networks (IN), a program to allow central office switches to make use of external computers to perform certain functions. This made 800-number port- ability possible. By 1993, customers could move 800 numbers between carriers or request any vacant number from any carrier. 800-number portability is based on a database look-up; the originating local carrier performs a "database dip" when a caller dials a toll-free number. The nationwide database, which is accessed via the Signaling Sy