That's very long for a URL. Most serves have a limit on the length of the URLs they can handle.

Also, your XML is invalid. You have unescaped double quotes in a double quoted attributes value, and "<" is not allowed to appear in attribute values. You need to use "&quot;" and "&lt;". Parsers might excuse the latter, but the former will definitely result in an error.

TEXT="The flight # <101> "DEL" to "BLR" is ..."
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should be

TEXT="The flight # <101> "DEL" to "BLR" is ..."
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But to answer your question, you can use URI to build a URL (a kind of URI).

use URI qw( );

chomp( my $data = <<'__EOI__' );
<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE MESSAGE SYSTEM "h
+ttp://127.0.0.1/psms/dtd/message.dtd" ><MESSAGE><USER USERNAME="test"
+ PASSWORD="XXXXXX"/><SMS UDH="0" CODING="1" TEXT="The flight # <101> 
+"DEL" to "BLR" is delayed and it's revised time will be informed late
+r. Have a nice day!" PROPERTY="0" ID="1"><ADDRESS FROM="ValueFirst" T
+O="91XXXXXXXXXX" SEQ="1" TAG="some clientside random data" /></SMS></
+MESSAGE>
__EOI__

my $url = URI->new('http://api.url/psms/servlet/psms.Eservice2');
$url->query_form(
    data   => $data,
    action => 'send',
);

print "$url\n";
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