[Spce-user] Missing ACK after T.38 re-INVITE from provider

[Daniel Grotti]

Hi,
there is no ACK at all in the trace for the Re-invite transaction.
200 OK looks good.
The ACK from the provider should have as RURI the Contact header in the 
200OK and he must contains the Route headers taken from the Record-Route 
headers in the 200OK, in reverse order, as per RFC3261.

This is a problem on your provider, as far as I can see.

Daniel





On 3/7/19 6:16 PM, Nate Baker wrote:
> Hello Everyone,
>
> I'm having an issue with sending faxes using T.38 (receiving works 
> fine) when the provider sends the re-INVITE. This is with SPCE 6.5.3, 
> and the problem is that after sending the 200 OK for the re-INVITE, we 
> never get an ACK back.  After looking at packet captures and working 
> with the provider, we think it has to do with the record-route 
> headers.  The provider says we shouldn't send them at all, but I think 
> they might just be reversed.  Could someone please take a look at the 
> attached exchange and let me know if the record-route headers in the 
> 200 OK after re-INVITE look correct?  It seems to me that they are 
> reversed, since in the original INVITE and ACK they are in opposite 
> order, so I'm thinking they can't route the ACK back to us.  Then our 
> SPCE keeps resending the 200 OK, and eventually the call hangs up.  If 
> there's a better way to send the trace let me know!
>
> If I make the provider not send the re-INVITE, and our end sends it 
> instead, the call works fine.  I've also tried using "topos" to hide 
> the record-route headers, but in that case SPCE sends ACKs from the 
> wrong interface so it doesn't work either (probably separate problem).
>
> Thanks,
> Nate Baker
>
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