$re = '/^1{1}(3{1}\d{1}|5{1}[012356789]{1}|8{1}[035689]{1})\d{8}$/m';
$str = '15011020699';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php