$re = '/(?i)(?<=QUOTE )\d+/m';
$str = 'So# Comments
1 sjhsh QUOTE 234566
1 sdsds customer call QUote 239876 Call back
2 adsdfh unknown call from customer QUOTE 189067 sdkjsd woieweio
3 QUOTE 657894 customer called for service';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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