In order to have the phone number in french format, i modified the include/class.format.php this way :
function phone($phone) {
$stripped= preg_replace("/", "", $phone);
if(strlen($stripped) == 7)
return preg_replace("/({3})({4})/", "$1-$2",$stripped);
elseif(strlen($stripped) == 10)
//return preg_replace("/({3})({3})({4})/", "($1) $2-$3",$stripped);
return preg_replace("/({2})({2})({2})({2})({2})/", "$1 $2 $3 $4 $5",$stripped);
else
return $phone;
}