Overview#

National Destination Code (NDC or NXX), commonly referred to as an International City Code or Number Plan Area or Area Code or significant leading digits of National Significant Number, is specified in ITU-T E.164.

National Destination Code identifies the Number Plan Area that is to be used.

National Destination Code optional code field which determined by each specific Telephone Numbering Plan.

National Destination Code when combined with the Subscriber Number (SN) - will constitute the National Significant Number within the international E.164-number for geographic areas.

National Destination Code North American Numbering Plan (NANP) #

North American Numbering Plan (NANP) National Destination Code values are available.[2]

The following 555-XXXX National Destination Code line numbers remain in use:

• 555-1212 Directory Assistance National use
• 555-4334 Assigned National use
• 555-0100 through 555-0199 are fictitious non-working numbers reserved for entertainment/advertising.

More Information#

There might be more information for this subject on one of the following:

• E.164
• Easily Recognizable Code
• International Direct Dialling
• International Telephone Number
• Mobile Global Title
• Mobile Station International Subscriber Directory Number
• NDC
• NXX
• National Significant Number
• North American Numbering Plan
• Number Plan Area
• Telephone Numbering Plan

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• [#1] - Telephone_numbering_plan - based on information obtained 2017-12-19-
• [#2] - Central Office Code Assignment Records - based on information obtained 2019-08-15
• [#3] - 555 NXX Line Number Reference Document - based on information obtained 2019-08-15