[asterisk-users] Asterisk 11 with t38modem 2.0: "488 Not acceptable here"

[Carsten Maass]

Hello all,

we do have a problem here with Asterisk 11 talking T.38 to a t38modem
2.0. The callflow is:

ISDN PRI --> Berofix (10.1.1.150) --> Asterisk (10.1.1.148) --> t38modem
(10.1.1.148) --> Hylafax [1]

Although the call gets connected, both parties are unable to negotiate
the audio codecs:

[2013-01-23 21:59:57] VERBOSE[8805][C-00000000] chan_sip.c: Got T.38
offer in SDP in dialog 237c0a65027630cd0c8bf2e70b5b3dc7 at 10.1.1.148:5060
[2013-01-23 21:59:57] VERBOSE[8805][C-00000000] chan_sip.c:
Capabilities: us - (alaw), peer -
audio=(nothing)/video=(nothing)/text=(nothing), combined - (nothing)
[2013-01-23 21:59:57] VERBOSE[8805][C-00000000] chan_sip.c: Non-codec
capabilities (dtmf): us - 0x1 (telephone-event|), peer - 0x0 (nothing),
combined - 0x0 (nothing)
[2013-01-23 21:59:57] VERBOSE[8805][C-00000000] chan_sip.c: Got T.38
Re-invite without audio. Keeping RTP active during T.38 session.

which results in a "SIP/2.0 488 Not acceptable here" from the Asterisk
and the call gets disconnected.

Asterisk full log with SIP trace is at http://pastebin.com/NNr6BTdp

This looks a lot like
https://issues.asterisk.org/jira/browse/ASTERISK-15596 which doesn't
seems to be solved by now.

Is this still a known issue in Asterisk 11? What can I do to make
Asterisk 11 play nice with t38modem v2.0?


Environment:
--------------
Red Hat Enterprise Linux Server release 6.3 (Santiago)

Linux myhost.mydomain.local 2.6.32-279.19.1.el6.x86_64 #1 SMP Sat Nov 24
14:35:28 EST 2012 x86_64 x86_64 x86_64 GNU/Linux

T38Modem Version 2.0.0
 (OPAL-3.9.0/3.9beta0, PTLIB-2.9.0/2.9beta0 (svn:24165)) by Vyacheslav
Frolov on Unix Linux (2.6.32-279.19.1.el6.x86_64-x86_64)

Asterisk 11.1.0
Hylafax 6.0.6


Thanx in advance and greetings,
Carsten.


[1] Yes, I know: the Berofix appliance can talk directly to the
t38modems, which works perfectly well here. But there is a limitation of
140 SIP Accounts in the Berofix and we have to serve ~500 fax numbers.
So we had to set Asterisk between the Berofix and the t38modems, bearing
the SIP accounts.


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