WPF Masked Textbox with a value that does not contain mask

I need a WPF Textbox that displays a phone number as "(555) 555-5555" but has a value of "5555555555".

All of the examples I'm seeing have the ability to mask the control on the UI but that affects the bound prop开发者_如何学运维erty of my view model so that the property value has the extraneous ()- characters.

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How about an IValueConverter?

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I am thinking that you will probably have to roll-your-own. It shouldn't be too difficult, subclass and override to obtain the results you are looking for.