Should I use an en dash or a hyphen in a phone number?

It really depends on the context and the font. Use whichever looks the best in a case-by-case situation. Depending on the font, adjusting the kerning on both sides of the dash/hyphen may be more important than which punctuation mark you end up using.

The easiest way to avoid dash/hyphen drama is to use periods or spaces instead: phone: 212.555.1000 phone: 212 555 1000 Both look more modern and visually appealing, at least to me. (No parentheses either... everyone knows what an area code is.)

My practice is to use non-breaking hyphens. I often work with hyphenated numbers, including phone numbers, within paragraphs. If the text reflows, I don't want such numbers to separate at the margins, or break across columns, pages, etcetera.

Functionally, because it's just a separator for ease of reading, a hyphen makes the most sense. A dash is used for ranges, which a phone number is not.

Some designers use a period. Many publications use hyphens because the type is set by data entry operators instead of designers/typographers. For the purposes of conventional print and signage, use an en dash or develop a style of your own, but a hyphen is just lazy.

The official answer according to the http://en.wikipedia.org/wiki/International_Telecommunication_Union (ITU) in standard http://en.wikipedia.org/wiki/E.123 is that phone numbers should use a space and not hyphen or en-dash; and that you should use parenthesis to enclose optional parts of a national phone number. So officially, a phone number for country code +1 (NANPA) it is either: (212) 555 1212 (national format) +1 212 555 1212 (international format) Typographically, if you are going to use a dash, it should be a hyphen since you are separating what is properly contiguous text.  Same as if you were breaking up a word (e.g., "Pat works part-time" would not use an en-dash). Pragmatically, there is benefit in writing it so that the phone number can be easily selected and copied by double clicking (when used in electronic text).  This makes it easier to select and dial a number on a cell phone or computer.  E.g., 212.555.1212 (vs. 212 555 1212 or even 212-555-1212). Realistically,  there are no phone-number police.  So just do whatever seems to work best in the your context based on function and design.

Only high-end fields that would be concerned about it would be english teachers, grammarians, and editorial people--i.e, people who work with words professionally. For the rest of us, it's a free-for-all. en dashes are usually used in number ranges, like "refer to pages 25–38". hyphens are the common separators for phone numbers. But I've alternately used spaces, periods, middle dots, over the years. The key is: is it easily readable. Definitely work with the kerning with whatever you use so it doesn't look too wonky—which can happen depending on the particular typeface you use.

As Raj Bhuptani mentioned in his answer, dot sounds sleek and stylish to me too, more than the dash. Another reason I personally use the dot because it is easier to type the dot on the phone, to use the hyphen or a dash of any sort you have to switch the keypad to a different one. The dot appears on the numeric keypad.

I agree with Stephen Coles;  design consistency is more important than being academically typographically correct. Its important to understand when to forgo the minutiae of 'typographic rules' and try new things ex... [212] 555~ 1212 212.555.1212 2 1 2 . 5 5 5 . 1 2 1 2