OBI200: T.38 faxing - how does it work?

[dhobi]

First of all, does it work with Google Voice?

And how does it work in general? Do you still need a fax machine at the sending end or can I just connect from the computer directly via IP (maybe using dedicated software)? If that were possible, I guess I would not need an OBI at all, but that would require the other side to support T.38

Also, what settings do I need to use on a fax machine so that faxing via GV is reliable? 9600 baud and disable error correction?
Thank you.

[LTN1]

To receive a fax with the Obi200, you will need a physical fax machine connected. To send a fax, you don't need an Obi200 or a fax machine, you just need your computer, a scanner and fax modem. But let's just focus the response.

You can use Google Voice with the Obi200 to receive and send faxes quite reliably with a fax machine connected. From my testing, if a landline is 99.99% reliable for faxing, the Obi200 is 97% when configured at 14000 bps and likely higher at 9600 bps. If using the Obi200 with a premium VoIP service like CallCentric, the reliability for faxing is closer to 99%.

[Ostracus]

T.37 would be more an IP way for those who have machines that can do it (it interfaces with something most understand, Email). Also T.38 doesn't always mean going over the PSTN especially for Internet aware fax machines.

[dhobi]

Some are suggesting to disable error correction when using GV. Did you find it to work better with it disabled? Couldn't that potentially result in a garbage fax at the other end but still get an OK status on your end?

[Trev]

Some are suggesting to disable error correction when using GV. Did you find it to work better with it disabled? Couldn't that potentially result in a garbage fax at the other end but still get an OK status on your end?

It sure could result in a garbage fax, and indeed you'll never know.  That's what ECM is there to help with.

It'll retransmit any parts that didn't make it and also confirm each line has been sent properly.

ECM does not need to be, and should not be, disabled with a properly functioning T.38 stack.

[LTN1]

With the OBi200, I don't think it is necessary to turn on ECM. You can also leave it at 14,000 bps instead of 9,600. The OBi really does a great job in the transmission, even with a noisy connection (by that I mean for faxing) like GV.

What I have found when faxing with the OBi200 via a GV connection is that there may be small evidences that not 100% of the contents make it through. It is sort of minor but you may see a streak through one of the lines. When using a standard VoIP line like CallCentric and the OBi200, you will find the transmission near perfect. Overall, the OBi200 will make VoIP faxing reliable, even when using GV.

[thogan]

I'm wondering if you can tell me what make and model Fax machine you used to successfully send and receive faxes using Google Voice?  I am able to send ok but can't seem to receive getting the message "no answer" or just "failed". 

[SteveInWA]

thogan:  please don't cross-post the same issue you posted elsewhere.  It makes it too difficult for other users to benefit from the discussion.

See this:  http://www.obitalk.com/forum/index.php?topic=8691.0

[LTN1]

thogan...I have a Brother MFC-8860DN.

[Webslinger]

First of all, does it work with Google Voice?

Google Voice does not support the T.38 protocol
You'll just be using the G.711u codec when faxing with Google Voice.