You can use three input boxes or use a regex validator.

>Hello all,
>
>I have a visual foxpro textbox control that uses the following properties to format a phone number:
>
>

>*--Displays the format mask for the text box that is specified in the
>*--InputMask property. The mask formats data for easier entry and clearer
>*-- display, but is not stored as part of the data.
>mytextbox.format = R
>
>mytextbox.inputmask =(999) 999-9999
>

>
>I would like to get a similar functionality in a web textbox control ( asp.net with c# ).
>I have been browsing helps files but can not find anything.
>
>Any feedback is appreciated.
>
>Thanks,
>Sergio