public ConnectionViewModel{    private readonly CollectionView _phonebookEntries;    private string _phonebookeEntry;    public CollectionView PhonebookEntries    {        get { return _phonebookEntries; }    }    public string PhonebookEntry    {        get { return _phonebookEntry; }        set        {            if (_phonebookEntry == value) return;            _phonebookEntry = value;            OnPropertyChanged("PhonebookEntry");        }    }}

The _phonebookEntries collection is being initialised in the constructor from a business object. The ComboBox XAML looks something like this: