Asterisk PJSip B2BUA - CSeq Increment Issue

I have an asterisk setup where my asterisk sits in like a B2BUA.

Call Flow:

Endpoint1 ↔ Asterisk ↔ Endpoint2

Asterisk does the routing and create an invite and handles the dialogs to both sides. However, I am seeing CSeqs not incremented per RFC 3261.

I will explain a call here step by step:

  • Call starts from Endpoint2, Invite received on Asterisk with CSeq: 1 INVITE
  • Asterisk routing decides to go to Endpoint1, INVITE send out with Cseq: 31053 INVITE

It’s all good here.

When the Endpoint1 side decides to hang up the call, Asterisk receives a BYE message from Endpoint 1 with CSeq: 31054 BYE.

Asterisk receives this BYE message and sends out a BYE message to Endpoint2 with CSeq: 27191 BYE, which I think should have been Cseq: 2 BYE

Could you please help me understand why I am seeing this what are the potential mistakes I am making?

You’re seeing this because that’s the way it works, and there’s no issue. The CSeq is independent in each direction.

Endpoint2 to Asterisk has an incrementing CSeq.
Asterisk to Endpoint2 has a different incrementing CSeq.

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