Let's study a little piece of Visual FoxPro help on Format Property

"R 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 (for example, if the mask is 99-999, the number 12345 is displayed as 12-345), but is not stored as part of the data. Use only with character or numeric data. "
So:

	ThisForm.TextBox1.Format="R"
	Thisform.Textbox1.InputMask="(999) 999-9999"

That's all.
Enjoy!

Radu Borzea