In the last 3 companies I\'ve worked at, the phone number columns are of type varchar(n). The reason being that they might want to store extensions (ext. 333). But in every
Personally, I wouldn't strip out any characters, as depending on where the phone number is from, it could mean different things. Leave the phone number in the exact format it was entered, as obviously that's the way the person who typed it in is used to seeing it.