The 1984 AT&T breakup gave rise to many small companies intent upon competing in the long-distance market. These included the then-fledgling Sprint and MCI, both of whom had only recently entered the marketplace. At the time, there was no way to switch a phone line to have calls automatically carried by non-AT&T companies. Customers of these small long-distance operations would be required to dial a local access number, enter their calling card number, and finally enter the area code and phone number they wish to call. Because of the relatively lengthy process for customers to complete a call, the companies kept the calling card numbers short – usually 6 or 7 digits. This opened up a huge vulnerability to phone phreaks with a computer.