asterisk users - Jun 2018 - T-38 re-invite issue

I have an error sending to a specific fax number.  It may be more than
one but this is the one I investigated.  It seems the delay for the SIP
negotiation in T.38 was initiated after 6 seconds, however, our system
sent the BYE after only 4 seconds, possibly cutting the call before all
the communication necessary for the negotiation was completed.  Here is
the trace from our provider showing their successful call to the number
and our failure.

FAIL:
2018-06-01 08:34:16.475 - Detected CED modem tone       ***********
Universal Media Gateway MGW02-EDTMTDS
2018-06-01 08:34:16.911 - Detected CEDPR modem tone
Universal Media Gateway MGW02-EDTMTDS
2018-06-01 08:34:20.692 - Incoming SIP message received : BYE From:
5555551111 at tor.trk.tprm.ca To: 5555552222 at 206.80.250.100
5555552222 at 209.197.130.80:5060        **********
MetaSphere CFS Distributel-Western-CFS
555-555-1111: Vybe Networks Inc. 98.158.139.74

SUCCESS:
2018-06-01 08:30:56.959 - Detected CED modem tone   ***********
Universal Media Gateway MGW02-EDTMTDS
2018-06-01 08:30:57.388 - Detected CEDPR modem tone
Universal Media Gateway MGW02-EDTMTDS
2018-06-01 08:31:03.187 - Detected V.21 flag fax tone     *********
Universal Media Gateway MGW02-EDTMTDS
2018-06-01 08:31:03.188 - SIP media renegotiation has commenced.
MetaSphere CFS Distributel-Western-CFS
555-555-3333 NxGen Networks Inc. 192.243.214.73
2018-06-01 08:31:03.188 - Outgoing SIP message sent : INVITE (SDP) From:
5555552222 at 208.68.17.52 To: 5555553333 at 10.0.5.61 192.243.214.73:5060
  *********
MetaSphere CFS Distributel-Western-CFS
555-555-3333 NxGen Networks Inc. 192.243.214.73

I tried increasing the t38timeout but it did not seem to have any
effect.  Is there another variable to adjust somewhere?

-- 
D'Arcy J.M. Cain
Vybe Networks Inc.
http://www.VybeNetworks.com/
IM:darcy at Vex.Net VoIP: sip:darcy at VybeNetworks.com

On 2018-06-08 06:45 AM, D'Arcy Cain wrote:
> I tried increasing the t38timeout but it did not seem to have any
> effect.  Is there another variable to adjust somewhere?
Pinging the list to see if anyone has any thoughts.  Perhaps someone can
explain what t38timeout is supposed to do as it seems to have no effect
at all.  It certainly doesn't seem to increase the time that it waits
for a T38 re-invite.


-- 
D'Arcy J.M. Cain
Vybe Networks Inc.
http://www.VybeNetworks.com/
IM:darcy at Vex.Net VoIP: sip:darcy at VybeNetworks.com

On 2018-06-08 06:45 AM, D'Arcy Cain wrote:
> I tried increasing the t38timeout but it did not seem to have any
> effect.  Is there another variable to adjust somewhere?
Pinging the list to see if anyone has any thoughts.  Perhaps someone can
explain what t38timeout is supposed to do as it seems to have no effect
at all.  It certainly doesn't seem to increase the time that it waits
for a T38 re-invite.


-- 
D'Arcy J.M. Cain
Vybe Networks Inc.
http://www.VybeNetworks.com/
IM:darcy at Vex.Net VoIP: sip:darcy at VybeNetworks.com

>>>>> "DC" == D'Arcy Cain <darcy at
VybeNetworks.com> writes:
DC> Perhaps someone can explain what t38timeout is supposed to do

A 'git grep t38timeout' on the src leads one to res/res_fax.c, where one
case see that it is the number of miliseconds to permit for t38 negotiation
to complete once it starts.

Ie after both sides select t38, until they agree on the t38 terms.

-JimC
-- 
James Cloos <cloos at jhcloos.com>         OpenPGP: 0x997A9F17ED7DAEA6