Analysing the traffic difference between Perl and Lynx gives me this:

Lynx sends in one frame POST & URL & field values.
while Perl sends only POST & URL without field values,
then Perl waits(?) for an 'ACK'
and then it sends the field values in another frame and is redirected to the initial page.

Is there anything to change this behviour?
This is my code to to get the next form:

BEGIN { *LWP::UserAgent::redirect_ok = sub {1} }
$ub = LWP::UserAgent->new;
$ub->agent($MOZILLA);
$res = $ub->request($form[1]->click('image',0,0));
# or this: $res = $ub->request(POST $URL, @TEL);
[download]

LYNX-TRAFFIC:

Frame 7 (668 on wire, 668 captured)
..
Hypertext Transfer Protocol
    POST /sms/austria.php3 HTTP/1.0\r\n
    Host: subscriber.chello.at\r\n
    Accept: text/html, text/plain, application/x-perl, image/jpeg, ima
+ge/*, application/x-gunzip, application/x-gzip, application/x-bunzip2
+, application/x-tar-gz, video/*, text/sgml, application/postscript, *
+/*;q=0.01\r\n
    Accept-Encoding: gzip, compress\r\n
    Accept-Language: en\r\n
    Pragma: no-cache\r\n
    Cache-Control: no-cache\r\n
    User-Agent: Lynx/2.8.4rel.1 libwww-FM/2.14 SSL-MM/1.4.1 OpenSSL/0.
+9.6c\r\n
    Referer: http://subscriber.chello.at/sms/index.php3\r\n
    Content-type: application/x-www-form-urlencoded\r\n
    Content-length: 33\r\n
    \r\n
    Data (33 bytes)

0000  61 75 73 74 72 69 61 3d 34 33 36 39 39 26 69 6d   austria=43699&
+im
0010  61 67 65 2e 78 3d 30 26 69 6d 61 67 65 2e 79 3d   age.x=0&image.
+y=
0020  30                                                0
[download]

Frame 7 (246 on wire, 246 captured)
...
  Hypertext Transfer Protocol
    POST /sms/austria.php3 HTTP/1.1\r\n
    Connection: close\r\n
    Host: subscriber.chello.at\r\n
    User-Agent: Perl/sms.pl\r\n
    Content-Length: 33\r\n
    Content-Type: application/x-www-form-urlencoded\r\n
    \r\n

Frame 8 (66 on wire, 66 captured)
..
    Flags: 0x0010 (ACK)
        0... .... = Congestion Window Reduced (CWR): Not set
        .0.. .... = ECN-Echo: Not set
        ..0. .... = Urgent: Not set
        ...1 .... = Acknowledgment: Set
        .... 0... = Push: Not set
        .... .0.. = Reset: Not set
        .... ..0. = Syn: Not set
        .... ...0 = Fin: Not set

..
Frame 9 (99 on wire, 99 captured)
..
  Hypertext Transfer Protocol
      Data (33 bytes)

  0000  61 75 73 74 72 69 61 3d 34 33 36 39 39 26 69 6d   austria=4369
+9&im
  0010  61 67 65 2e 78 3d 30 26 69 6d 61 67 65 2e 79 3d   age.x=0&imag
+e.y=
  0020  30                                                0


Frame 10 (294 on wire, 294 captured)
..
 Hypertext Transfer Protocol
    HTTP/1.1 302 Found\r\n
    Date: Wed, 07 Aug 2002 10:15:45 GMT\r\n
    Server: Apache/1.3.26 (Unix) PHP/4.2.1\r\n
    X-Powered-By: PHP/4.2.1\r\n
    Location: /sms/index.php3\r\n
    Connection: close\r\n
    Transfer-Encoding: chunked\r\n
    Content-Type: text/html\r\n
    \r\n
    Data (5 bytes)

  0000  30 0d 0a 0d 0a                                    0....
[download]

I don't think the fact that the TCP stream is fragmented into multiple packets is likely to be causing your problem.

One possibility is that the server logic expects a referer header:

Referer: http://subscriber.chello.at/sms/index.php3

I've got it!

The servers denied to go on unless the correct Referer is entered in the header. LWP does not do by it self.

Thanks for your hints,
Carl

I'll let you know, if you are interested,
Carl
(carl.schreiber@web.de)