How would I write a validation expression for a Phone number

I'm trying to figure out how to write a validation expression that would allow these formats : (xxx)xxx-xxxx , 123456789


anyone know of any validation expressions that is somewhat like that or exactly like that or better ?

Take a look at http://regexlib.com/

well, for your first example (xxx) xxx-xxxx , the expression would be
^\([2-9]\d{2}\) \d{3}[- .]?\d{4}\D*(\d*)$

and for your second example, xxxxxxxxxx , the expression would be short and simple....
^\d{10}$


good luck!