456xx

456xx is a series of telephone numbers in the North American Numbering Plan (NANP) that are reserved for special services and testing purposes. The prefix "456" is assigned to the Canadian province of Ontario, but the "xx" portion is not used for regular telephone numbers. Instead, it is used for various special services, including:

1. Test numbers: These numbers are used to test telephone systems and equipment. They are not assigned to any specific location and do not connect to a live person or service.

2. Emergency services: Some 456xx numbers are reserved for emergency services, such as 456-1234 for the Canadian Red Cross.

3. Special services: Other 456xx numbers are reserved for special services, such as 456-7890 for the Canadian National Railway.

The use of 456xx numbers is regulated by the Canadian Radio-television and Telecommunications Commission (CRTC) and the North American Numbering Plan Administrator (NANPA). The CRTC is responsible for assigning and managing telephone numbers in Canada, while the NANPA is responsible for coordinating the use of telephone numbers in North America. The use of 456xx numbers is subject to certain rules and regulations, including the requirement that they be used only for special services and testing purposes.