You didn't make yourself clear but I'll give it a shot.
You are validating a phone number as an integer.
Java's max integer value is 2^31-1 that's 2147483647 and if I count correctly that's a 10 digit number. Go above this and you don't have an integer any more.
The rest is up to you to figure out. Use regexp to validate it and store it in varchar that would be a solution.