Phone Number Validation Control

<asp:RegularExpressionValidator ValidationGroup="EVSContactUs" Display="None"
                                            ID="RegularExpressionValidator2" runat="server"
                                            ErrorMessage="Please enter valid contact number."
                                            ControlToValidate="txtContact" ValidationExpression="^\+?\d*\-?\ ?\d*\-?\ ?\d*$"></asp:RegularExpressionValidator>