$re = '/(\d\.).+\d\s(\w+)\s:/m';
$str = 'GSM NWS\\TOP N Pool 1\\1. TOP N Pool 1 Rank :
GSM NWS\\TOP N Pool 1\\1. TOP N Pool 1 BCCH :
GSM NWS\\TOP N Pool 1\\1. TOP N Pool 1 BSIC :
';
$subst = "$1$2";
$result = preg_replace($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