Portability, a program instituted by the FCC in May 1993, gives ownership of a particular toll free number to the company using it, not the carrier. As a result, any company can switch carriers without losing the marketing equity invested in a particular number. Switching carriers is as simple as calling a new carrier and signing up for service.

Portability also allows businesses to split toll free traffic on a given number across multiple carriers. For example, all in-state calls could be handled by the local telephone company while out-of-state calls could be handled by a national carrier.