Hello,

indeed, the Record-Route address must be local to the server adding it, asking to retrieve the subsequent requests within the same dialog.

Adding the address in Record-Route of other node in the network doesn't make much sense, especially when there is no relation between them.

I have seen SIP stacks adding Route header with the IP of the outbound proxy for initial requests, which is also disputable in terms of how valid it is, but at least is for the current request sent anyhow to that hope, not requesting a node to send traffic to another node.

Likely a bug or misconfiguration in the SBC.

Cheers,
Daniel

On 17/01/2017 19:40, Andres wrote:

Hi,

I am troubleshooting some strange call setup problems using an Edgewater Networks SBC.  A couple of Polycom phones sit behind the SBC and they connect to a SIP Server in the cloud.  The SBC is in passthrough mode.

What I see that I am not sure about is:
INVITE from SIP Server to SBC IP (no Record-Route header...so far no surprise here)
INVITE from SBC to Phone (Record-Route header inserted by SBC but with the IP of the SIP Server)

I do not think the SBC is supposed to add a Record-Route header with the IP of the remote SIP Server.  I think It should only be allowed to add Record-Route headers with its own IP.  Does that sound right?

The RFC lists the usage as:

"20.30 Record-Route

   The Record-Route header field is inserted by proxies in a request to
   force future requests in the dialog to be routed through the proxy."

It says nothing about being able to arbitrarily force future requests to go through a remote IP.

Please advise.

Thanks,

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