Editing Interexchange carrier (section)

== Carrier identification code ==
Each carrier (interexchange or local exchange) is assigned a four-digit identification code, the '''carrier identification code''' ('''CIC''') which was used with [[feature group]]s. The interexchange carrier to which calls from a subscriber line are routed by default is known as the '''presubscribed interexchange carrier''' ('''PIC'''). To give telephone users the possibility of opting for a different carrier on a call-by-call basis, '''carrier access codes''' ('''CAC''') were devised. These consist of the digits 101 followed by the four-digit CIC. The CAC is dialed as a prefix immediately before dialing a long-distance telephone number.

In popular usage, CACs are often referred to as '''dial-around codes''', because they allow "dialing around" the PIC. Sometimes they are even called "PIC codes", though this term is inaccurate, since the code is being used to ''avoid'' the PIC, not to use its services.

When CICs were first introduced in 1983, they were only three digits long, and the CAC consisted of the digits 10 followed by the three-digit CIC. In 1998, the CIC had to be extended to four digits. Existing carriers' codes were prefixed with 10. Thus, a pre-1998 CAC of the form 10-XXX became 101-0XXX.<ref>See the [http://www.fcc.gov/Bureaus/Common_Carrier/FAQ/cic_faq.html FCC's FAQ] on the subject.</ref> Since the CACs starting with 10-10 are generally the oldest and best-known ones, CACs are sometimes referred to as '''10-10 codes'''.