string format

Question

How does one format a phone number so it renders like:

[phone]

<asp:FormView id="formview1" DataSourceID="SqlDataSource1" runat="server" DataKeyNames="EFxID">
  <ItemTemplate>
      Cell Phone:
        <asp:Label id="lblCellPhone" runat="server" Text='<%# Bind("ECellPhone")%>' />
  </ItemTemplate>
</asp:FormView>