If they are already numbers then you can use
format, cells, special, phone numbers
which for English(US) would provide the equivalent
of a format, cells, custom
[<=9999999]###-####;(###) ###-####

Personally I would only enter phone numbers as text,
and because of where I live, I have to dial all digits
anyway I would use the custom format of
000-000-000

But if you really want to things right, I'd use text
entries then no matter what you type would be used and you
could include foreign phone numbers and/or additional codes or
extensions.

to format a text string you would have to use a macro or a
user defined function

If they are 10 digits of text, you could force them to a number within your formula
and format, the result would be a string.
=TEXT(A28 + 0, "\(000\) 000\-0000")