I have a xamgrid which contains a template column which has a xamcombobox as its ItemTemplate.  I have the grid bound to an observable collection of class "Contact".  Each Contact has an observableCollection of strings(these are all the phonenumbers for the contact).  I want to display these phonenumbers in the combobox within the rows of the grid for each contact.  How do I bind this?  Have been trying different syntax and cant seem to get it correct.  I have the combo showing, but no data is displaying in it.