How 511 got its digits

Before 1996, three-digit N11 dialing codes were administered on a largely ad hoc basis by local jurisdictions and by local and national telecommunications carriers. But the Telecommunications Act of that year gave the Federal Communications Commission exclusive jurisdiction of numbering administration, including the use of abbreviated dialing codes.

Because the digits 1 and 0 are used for telephone switching and routing, there were only eight of these numbers available (211 through 911), making them what FCC called “among the scarcest of numbering resources under our jurisdiction.”


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In 1999, the Transportation Department petitioned FCC to assign 511 nationally for access to travel information. The department said state-of-the-art intelligent transportation systems maintained by state and local jurisdictions around the country could provide valuable information to travelers about road conditions, traffic and travel times but added that the resources were underused because there was no single convenient way to access them. Having a single three-digit number available would encourage greater use of the services, which in turn would reduce traffic congestion and pollution, lower fuel consumption, and improve safety, DOT said.

By that time, six of the eight available numbers already were in use:

  • FCC had allowed carriers to continue using 611 and 811 for access to local telephone repair services.
  • FCC allowed the continued widespread use of 411 for directory assistance.
  • Congress had directed that 911 be used for emergency services.
  • FCC had assigned 311 for access to nonemergency police and other government services, and 711 for access to Telecommunications Relay Services for those with hearing and speech disabilities.
That left 211 and 511 to be assigned.

In an order in July 2000, FCC granted the DOT petition to assign 511 for travel information services and separate petitions to assign 211 for access to community referral and information services.

About the Author

William Jackson is a Maryland-based freelance writer.

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