//$hp = "01012345678";

$hp = "010.1234.5678";

$hp = preg_replace("/[^0-9]/", "", $hp);

echo preg_replace("/([0-9]{3})([0-9]{3,4})([0-9]{4})$/", "\\1-\\2-\\3", $hp);

결과 값 : 010-1234-5678