Raise custom event in user control, handle in page

 I have user control called PhoneNumber.ascx it consites of a DropDownList of countries and textbox for phone number. On SelectedIndexChange of the DropDownlist I want to raise an event that the using page can handle.
I have Autopostback enabled and the index change event is happening just the call page can't seem to catch it! Below is a subset of the code:

public partial class PhoneNumberControl : System.Web.UI.UserControl
    {

        public event EventHandler CountryChanged;

        protected virtual void OnCountryChanged(EventArgs e)
        {
            if (CountryChanged != null)
            {
               ...