<?php
function add_hyphen($tel) {
    $tel = preg_replace("/[^0-9]/", "", $tel); // 숫자 이외 제거
    if (substr($tel,0,2)=='02')
        return preg_replace("/([0-9]{2})([0-9]{3,4})([0-9]{4})$/", "\\1-\\2-\\3", $tel);
    else if (strlen($tel)=='8' && (substr($tel,0,2)=='15' || substr($tel,0,2)=='16' || substr($tel,0,2)=='18'))
        // 지능망 번호이면
        return preg_replace("/([0-9]{4})([0-9]{4})$/", "\\1-\\2", $tel);
    else
        return preg_replace("/([0-9]{3})([0-9]{3,4})([0-9]{4})$/", "\\1-\\2-\\3", $tel);
}

function br2nl($string) {
    return preg_replace('/\<br(\s*)?\/?\>/i', "\n", $string); 
}