Regular Expression Help

I'm trying to figure out how to "say" with a Regular Expression how to check for the following characters in a phone number: ( ) - with a length between 1 and 20 -- I've tried the following and it doesn't seem to work. eregi("^([0-9]|\\(|\\)|\\-){1,20}$") I'm not interested in checking for a completely valid phone number... but instead checking to see if the phone number is numbers with or without the ( ) - characters. Plus, I think creating a Regex expr that can check for US and International formats would be too complex. Thanks. Jason