Freepbx and app_rxfax error: "Unable to find a codec translation path from ulaw to unknown"

I have successfully installed freepbx on top of Ubuntu 8.04, can call extension to extension, call in and out of a trunk, have voicemail set up, and receive emails of left voicemails.

I am now trying to get fax reception working – I have a dedicated SIP DID that I want to use for inbound faxing.

I installed the ubuntu package asterisk-app-fax. When I call the pre-configured special fax extension 666 from another PBX extension, I get the appropriate fax reception ‘canary calls.’ With an inbound rule set up, when I call the designated DID from outside the PBX (whether via SIP or PSTN), I get mapped to this extension with no problem, and receive the canary calls with no problem.

However, when I have a fax machine do the calling, the fax starts to go through, but then interrupts in the middle. Scanning the log file, the most relevant error messages seem to be that included below. Granted, they’re all warnings, but the bit about not finding a codec mapping concerns me.

Has anyone any idea what the problem could be here?

This is an excerpt from the log file ‘full’:

[Dec 18 00:02:56] DEBUG[24111] app_rxfax.c: ===========================================================================\

[Dec 18 00:02:56] DEBUG[24111] app_rxfax.c: Fax receive not successful - result (50) Disconnected after permitted retri
es.
[Dec 18 00:02:57] DEBUG[24111] app_rxfax.c: ===========================================================================\

[Dec 18 00:03:08] DEBUG[24111] app_rxfax.c: Got hangup
[Dec 18 00:03:08] WARNING[24111] channel.c: Unable to find a codec translation path from ulaw to unknown
[Dec 18 00:03:08] WARNING[24111] app_rxfax.c: Unable to restore read format on ‘SIP/ceb_mpbx-082121f0’
[Dec 18 00:03:08] DEBUG[24111] app_macro.c: Executed application: rxfax

This is an excerpt from an attached console with ‘set verbose 999’.

^@ – Executing [[email protected]:3] Macro(“SIP/ceb_mpbx-082121f0”, “faxreceive”) in new stack
^@ – Executing [[email protected]:1] Set(“SIP/ceb_mpbx-082121f0”, “FAXFILE=/var/spool/asterisk/fax/asterisk-22714-
1229554949.18.tif”) in new stack
^@ – Executing [[email protected]:2] Set(“SIP/ceb_mpbx-082121f0”, "[email protected]") in new stack
^@ – Executing [[email protected]:3] RxFAX(“SIP/ceb_mpbx-082121f0”, “/var/spool/asterisk/fax/asterisk-22714-122955
4949.18.tif”) in new stack
^@
– Executing [[email protected]:1] System(“SIP/ceb_mpbx-082121f0”, “/var/lib/asterisk/bin/fax-process.pl --to [email protected]
–from [email protected] --dest “9193233757” --subject “Fax from 41448103890 41448103890” --attachment fax_41448103890.p
df --type application/pdf --file /var/spool/asterisk/fax/asterisk-22714-1229554949.18.tif”) in new stack
^@
– Executing [[email protected]:2] Hangup(“SIP/ceb_mpbx-082121f0”, “”) in new stack
^@ == Spawn extension (ext-fax, h, 2) exited non-zero on ‘SIP/ceb_mpbx-082121f0’
^@
– Got SIP response 603 “Decline” back from 192.168.2.1