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456 NXX Codes

The purpose of NPA 456 and its associated NXXs is to enable the routing of inbound international calls for carrier-specific services, particular to a service provider's network, to and between NANP Area countries. This is accomplished by providing carrier identification within the dialled digits of the E.164 number. More specifically, the prefix following 456 (456-NXX) identifies the carrier. Use of these numbers enables the proper routing of inbound international calls destined for these services.

456-NXX codes are assigned according to the Industry Numbering Committee (INC) International Inbound NPA Assignment Guideline, as accepted or modified by the Canadian Steering Committee on Numbering. If you wish to apply for an assignment, fill out the application form included in the assignment guideline, and return it to the Canadian Numbering Administrator.


In 2017, the Industry Numbering Committee (INC) investigated the use of this resource in their networks and determined that there was no longer a need for the 456 NPA. INC agreed to sunset the ATIS-0300049, International Inbound NPA (INT/NPA/NXX) Assignment Guidelines and age the 456 NPA for five years before the NPA is returned to the general purpose code pool.

Currently there are no 456-NXX assignments


To access the Canadian Adjunct to the INC International Inbound (INT/NPA/NXX) Assignment Guideline, go to the CRTC website.

To access Appendix A - Audit Process and Forms, click here.

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