title: Implementing IDataErrorInfo in a view model
body: <p>I have a ViewModel class with a Phone object as one of its properties , my main window data context is set to the ViewModel, do I need to implement IDataErrorInfo on the underlying Phone model class or the ViewModel class that contains the Phone property?</p>
  
  <p>Also what would be the correct way to bind the textbox I'm trying to validate to my ViewModel.NewPhone.StringProperty?</p>
  
  <p>Many thanks</p>