struts2 regex validation for a phone number

Struts2 bundled (built-in) validator regex type could really have some better examples!

Here's a basic phone number regex sample for a standard North American telephone number e.g. 123-456-7890

Key point is to use start/end pattern indicators ^ and $ - otherwise 123-456-78901234 etc. will also match!

 <field name="person.phone">
 <field-validator type="required" circuit="true">
  <message>${getText("error.phone.required")}</message>
 </field-validator>
    <field-validator type="regex">
        <param name="expression"><![CDATA[^[\d]{3}-[\d]{3}-[\d]{4}$]]></param>
        <message>${getText("error.phone.format")}</message>
    </field-validator>
 </field>