UserAsdf,
I have reread your entries more carefully. You may still have a defective unit, however I can suggest a few other things to try.
Checklist
1) You
are certain that that the Service Provider supports T38 codec? From this reply it doesn't sound like it. Just to be clear, was it the OBiMAN voice or a CC voice message?
Quote from: UserAsdf on July 04, 2012, 04:20:21 PM
I've already tried disabling all codecs except T.38 a few days ago. That resulted in an error message saying something about the service provider not supporting the call or something.
2) You obviously have followed the CC fax FAQ (
http://www.callcentric.com/faq/30#205 )
Fax Machine: Try using the slowest possible speed on your fax machine. Normally 9.6k or 14.4k would be the best options, as speeds faster than 14.4k may not work properly with faxing. Disable error correction
T.38: Enable T.38.Disable echo cancellation and echo suppression. If available enable re-INVITE for faxes
Pass through:Try using the G711 codecs as these would offer more bandwidth.Disable echo cancellation and echo suppression Disable NSE, usually on Cisco/Linksys devices
Quote from: UserAsdf on July 02, 2012, 02:02:01 PM
At all times, the call status page shows G711 is in use. I would try forcing T.38 if I knew how.
I show a way how to force T38 codec up above. I assume you did the exact thing. You are certain that the fax is going over the CC trunk. I would try **1 or **2 before the fax number just to make sure you force it over the correct trunk. Since it shows using G711 it might be going over your GV account (if you have one, you didn't mention it).
Quote from: UserAsdf on July 04, 2012, 05:00:31 PM
The fax never even begins transmission because the answering fax machine's tones are being cut off by the Obi202 almost immediately.
I think that could be a symptom of many things including a codec issue, it may not have anything to do with a faulty OBi.
Failing the lack of proper Obihai documentation, I am forced to scavenge from other sources. We can find T38 Fax relay explained here: (May not be completely relevant to the OBi)
http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/cisco_ios_fax_services_over_ip_application_guide/t38.html#wp1158066SIP T.38 Fax Relay
•The transport protocols specified in the ITU-T recommendation for T.38 are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). However, for T.38 fax relay on Cisco gateways, only UDP is supported for the transport layer.
•If SIP T.38 fax relay is not supported by both gateways, the T.38 negotiation fails and the call reverts to an audio codec.
<-- NB This might be what is happening to you.•T.38 fax relay requires a 64-kbps transmission rate, the same amount of bandwidth as a voice call with the G.711 codec.
•Fax Calling Tones (CNG) are optional and are not used to initiate a switch to T.38 mode. Instead, Called Station Identifier (CED) tones or preamble flags are used.
•SIP fax relay does not rely on NSEs to signal a switch to T.38 mode. Standard RFC 2543 and RFC 2327 SIP and SDP signaling are used instead.
•If the fax rate disable command is configured on a dial peer, neither the originating nor the terminating gateway can enter into Cisco fax relay mode, T.38 fax relay mode, or fax pass-through mode. The fax rate disable command disables fax transfer support.
Hope this helps. I'm surprised that someone else with a CC fax setup has not replied to you directly.