<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
</head>
<body dir="ltr">
<div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr">
<br>
<div style="color: rgb(0, 0, 0);">
<div id="divRplyFwdMsg" dir="ltr"></div>
<div>
<div id="divtagdefaultwrapper" dir="ltr" style="font-size:12pt; color:#000000; font-family:Calibri,Arial,Helvetica,sans-serif">
<p></p>
<div>Dear OpenSIPS users,<br>
<br>
I'm facing a problem related to CSeq numbers in SIP messages and maybe it is being caused by SIP OPTIONS messages.<br>
When a caller sends a SIP ACK to the callee, the SIP ACK has CSeq = 2. However, after being relayed by OpenSIPS, the CSeq number become 3.<br>
It seems that OpenSIPS decided to change such value on its own. But, maybe it was caused by the previous SIP OPTIONS message receive before.<br>
The diagram bellow shows what is happening.<br>
<br>
Can the SIP OPTIONS message cause such issue? If yes, should I give up of using SIP OPTIONS? Can it be a bug in OpenSIPS?<br>
If not, what is happening here??<br>
If that CSeq remains like 3, the callee will simply discard the SIP ACK and send another SIP OK, will not discard?<br>
<br>
<br>
<br>
Caller                        OpenSIPs                          Callee<br>
|                                          |                                        |<br>
|                                          |                                        |<br>
|       INVITE                      |                                        |<br>
|       CSeq = 2                  |                                        |<br>
|------------------------------->|        INVITE                    |<br>
|                                         |        CSeq = 2                |<br>
|                                         |------------------------------->|<br>
<span>|                                         |                                         |</span><br>
|                                         |         TRYING                 |<br>
|                                         |         CSeq = 2               |<br>
|      TRYING                    |<-------------------------------|<br>
|      CSeq = 2                  |                                         |<br>
|<-------------------------------|                                         |<br>
<span>|                                          |                                        |</span><br>
|                                          |         RING                     |<br>
|                                          |         CSeq = 2               |<br>
|      RING                          |<-------------------------------|<br>
|      CSeq = 2                  |                                          |<br>
|<-------------------------------|                                          |<br>
|                                         |         SIP OK                   |<br>
|                                         |         CSeq = 2               |<br>
|      SIP OK                      |<-------------------------------|<br>
|      CSeq = 2                  |                                         |<br>
|<-------------------------------|                                         |<br>
|                                         |         SIP OK                   |<br>
|                                         |         CSeq = 2               |<br>
|      SIP OK                     |<-------------------------------|<br>
|      CSeq = 2                  |                                         |<br>
|<-------------------------------|                                         |<br>
<span>|                                         |                                        |</span><br>
|                                         |        SIP OPTIONS       |<br>
|                                         |        CSeq = 3                |        <<---- new CSeq<br>
|                                         |<-------------------------------|<br>
<span>|                                         |                                         |</span><br>
|                                         |         SIP 500                  |<br>
|                                         |         CSeq = 3               |<br>
|                                         |------------------------------->|<br>
|       ACK                          |                                        |<br>
|       CSeq = 2                 |                                         |<br>
|------------------------------->|        ACK                        |<br>
|                                         |        CSeq = 3                |      <<---- Cseq of ACK was changed by OpenSIPS.
<br>
|                                         |------------------------------->|<br>
|       ACK                         |                                          |<br>
|       CSeq = 2                 |                                         |<br>
|------------------------------->|        ACK                        |<br>
|                                         |        CSeq = 3                |<br>
|                                         |------------------------------->|<br>
<span>|                                         |                                         |</span><br>
|                                         |         SIP OK                   |<br>
|                                         |         CSeq = 2               |<br>
|      SIP OK                      |<-------------------------------|<br>
|      CSeq = 2                  |                                         |<br>
|<-------------------------------|                                         |<br>
|       ACK                         |                                         |<br>
|       CSeq = 2                 |                                         |<br>
|------------------------------->|        ACK                        |<br>
|                                         |        CSeq = 3                |<br>
|                                         |------------------------------->|<br>
<span>|                                         |                                         |</span><br>
|                                         |         SIP OK                   |<br>
|                                         |         CSeq = 2               |<br>
|                                         |<-------------------------------|    <<------- This SIP OK never receives a SIP ACK with CSeq = 2...and the problem continues.<br>
<br>
Any hint will be very helpful!!<br>
</div>
Best regards!<br>
<p></p>
<p><br>
</p>
<div id="Signature">
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<div class="BodyFragment"><font size="2">
<div class="PlainText">RODRIGO PIMENTA CARVALHO<br>
Inatel Competence Center<br>
Software<br>
Ph: +55 35 3471 9200 RAMAL 979<br>
</div>
</font></div>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>