RadMaskedTextBox does not return the literal (-) or prompt (_) characters in its Text
property. Only the user-entered value is returned, stripped of any literals in the mask itself. I have attached a small test page to demonstrate. Enter some digits and click the button to have the label show the RadMaskedTextBox.Text property.
Hiding the mask when the textbox is not focused is not supported. You can display a different mask when RadMaskedTextBox is blurred by setting the DisplayMask property, but you cannot remove the mask completely.
the Telerik team