public function PhoneFriendly()
    {
        $ReplacementMap = array(
            'a'=>'2', 'b'=>'2', 'c'=>'2',
            'd'=>'3', 'e'=>'3', 'f'=>'3',
            'g'=>'4', 'h'=>'4', 'i'=>'4',
            'j'=>'5', 'k'=>'5', 'l'=>'5',
            'm'=>'6', 'n'=>'6', 'o'=>'6',
            'p'=>'7', 'q'=>'7', 'r'=>'7', 's'=>'7',
            't'=>'8', 'u'=>'8', 'v'=>'8',
            'w'=>'9', 'x'=>'9', 'y'=>'9', 'z'=>'9',
            '+'=>'00',
            ' '=>''
        );
        $value = str_ireplace(
            array_keys($ReplacementMap),
            array_values($ReplacementMap),
            $this->owner->value
        );

        // Strip out everything else
        $value = preg_replace('/[^0-9\,]+/', '', $value);

        return $value;
    }