What is the rule about using parentheses in telephone numbers?

Since June 17, 2006, dialing the area code is mandatory for all local calls. That meant the same seven-digit telephone number could be used several times, which became necessary with growing demand for telephone numbers, especially since the cell phone has almost become the norm.

But what about the treatment of telephone numbers in print? The standard of placing the area code in parentheses to indicate that its use is optional no longer applies.

As the parentheses fall, a consensus on how to write the ten digits is far from being reached. Some add a hyphen between the prefix and phone number, many prefer to simply add a non-breaking space. What is the proper way to do this?

Here are the recommendations:

The Telecommunications Alliance and the Office québécois de la langue française recommend the use of a non-breaking space after the area code: 514 111-2222.

The Translation Bureau, the Canadian Steering Committee on Numbering (CSCN) and the North American Numbering Plan Administration (NANPA) who work with the CRTC recommend using a hypen: 514-111-2222.

In short, both methods are accepted now, and depending on the source consulted, neither one nor the other is a typographical error. However, the use of periods to separate digits should be prohibited: 514.111.2222.