CSeq for re-INVITE

[Sandra Gilge]

Hallo,

 

I’m using SIP Inspector 3.48 and have no experience with the tool yet.

I have following scenario (which simulates a SIP Callcenter of a customer):

<--- INVITE

---> 100

---> 180

---> 200

<--- ACK

 

---> INVITE (Invite for update (without SDP)

<--- 200

---> ACK (with SDP for late offer)

 

The INVITE that shall be sent is  a re-INVITE. Thus the Call-ID is the same as for the INVITE I got. (That is easy)

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- But the CSeq should be the last received CSeq + 1  -

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I tried to implement this with variables but I was not successful.

 

Best regards,

Sandra

 

 

[Zarko Coklin]

Hi Sandra!

As a side note, I can describe your scenario as:

1) B calls A

2) A then wants to update the session by sending out an INVITE (2nd one in your scenario). 

If that is the case, both these INVITEs can have their own CSeq numbers. B keeps track of its CSeq count, A keeps track of its own CSeq count. It is not required that INVITE from A needs to have a CSeq by one greater than the value that came with an INVITE from B.

Still, it is possible to achieve exactly that. The best would be to share SIP scenario you have so far. That way I can modify it, rather than write it from scratch..

Zarko