Hi sanjay nayak

You can have a quick reference about the perl regular expressions here http://perldoc.perl.org/perlrequick.html

Moreover in your example coding you misused the matching operator. It should be =~ and you may want something like this

if ($text =~ /^(?:REGISTER|INVITE|BYE)\s\w+[-@_]\w+\.\w+\sSIP\/2\.0/)
{
    print "IN:$text\n";
}
[download]

Punitha