[asterisk-users] T.38 not working - help needed with log interpretation

Frederic Van Espen frederic.ve at gmail.com
Wed Dec 10 04:42:54 CST 2014


On Tue, Dec 2, 2014 at 9:24 AM, Recursive <lists at binarus.de> wrote:
> - Packets 14313, 14314: The provider re-invites asterisk for T.38 (confirmed by viewing the packet's details), asterisk answers "Trying ..." to the provider
> - Packets 14315, 14321, 14322: Asterisk re-invites the local endpoint (again confirmed by looking into the packet's details), the local endpoint answers "OK", and asterisk ACKs the OK.
> - Packets 14323, 14329: Asterisk accepts the invitation from the provider by sending "OK" to the provider, and the provider ACKs the OK.
> - Packets 14453, 14454 and 14649: The local endpoint again tries to re-invite asterisk for T.38 (confirmed by looking into the packet's details), Asterisk answers "Trying" and then refuses, saying "488: Not acceptable here"
> - From then on, things go horribly wrong (probably, the local endpoint is still expecting G.711 packets, but gets T.38 packets)
> I have provided all packets which are relevant. The packet numbers are not contiguous since asterisk currently is on a test server which runs many other services (the packets of which I have filtered out).
> I didn't want to clutter this post too much, thus I have only provided an overview and not the details of each packet. Furthermore, please forgive me that it's much easier for me to read Wireshark's logs than Asterisk's logs. Of course, I will provide every log anybody trying to help out asks me for.
> But my first question is a very simple one:
> From the log above, I am quite sure that switching to T.38 is done right up to (and including) packet 14329. I think that my local endpoint then misbehaves by again re-inviting asterisk for T.38 (as all parties already have agreed upon T.38).
> Thus, is my endpoint really misbehaving, and if yes, is there anything I can do about it on Asterisk's side? Or do the SIP/T.38 state machines allow such (seemingly superfluous) re-invite, and it's Asterisk's fault to answer with 488?

- Could you share the details of the SDP in each INVITE and OK packet?
- How are your SIP endpoints configured in asterisk sip.conf? (the SIP
trunk provider and the local endpoint)
- What type is the local endpoint?



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