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<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>
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Best regards!<br>
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