function format_phnum($ac,$ph) {
	$areaCode = '(' . $ac . ') ';
	$npa = substr($ph,0,3) . '-';
	$num = substr($ph,3,4);
	return $areaCode . $npa . $num;
}

Use this to format a phone number for display on a page.

Format a phone number in PHP

php, format

PHP