But the changing isn't user visible. To the user, the phone number is the string "(416) 555-1270". If you want to store it differently in your database go ahead. But to the user, the phone number has dashes.

In fact, on my phone, when I type in just the digits, my phone inserts the parens and dashes. Presumably, users consider this easier to read, and dare I say, more canonical.

So, many applications can't handle phone number input in the exact form they display it to the user.

What’s jarring is that a field for phone numbers can’t parse dashes and spaces.