Sending fax problem
drgeoff:
Quote from: SteveInWA on June 09, 2019, 05:56:03 pm
.... the T.38 standard was developed, but it was largely a flop, due to lack of implementation by fax machines or terminals.
Fax machines and terminals which connect to analogue "lines" (POTS lines, analogue side of ATAs etc) do not implement T.38. That is the whole point. The purpose of T.38 is to "hide" the vagaries of IP and VoIP so that the end to end connection appears to the fax machines to be and to have the properties of a POTS path. No change to existing fax machines was required.
T.38 needs to be implemented at the junctions POTS* to VoIP and VoIP to POTS*. An ATA is one such location and OBi200/202/212/300/302 devices do have it. However it cannot function if T.38 is not present at the other point where POTS* and VoIP interchange. That is commonly where an ITSP connects its VoIP customers to POTS*.
(* These POTS are not necessarily analogue. More often they will be PCM, G.711.)
Thomike:
For Steve: here is my Internet speed. What else is needed?
If there are any, I would have greatly appreciated clear, perfectly operational instructions printed in the Polycom OBi200 Installation & Configuration Guide.
I also read that the OBi202 could fax on only one of its two lines. I can still change for this model if I was sure it would work.
For the time being, I would like to thank everyone for the suggestions provided. This will take time and multiple tests for a very uncertain result.
It is this situation that I strongly reproach Polycom Obihai for providing very interesting hardware but with fanciful promises to say the least.
drgeoff:
@Thomike
Your internet speed is not the issue. Fax machines use modems to communicate over POTS and those modem standards were devised (many years ago before VoIP) to accommodate the types of distortion and impairment that POTS suffers from. A VoIP circuit has completely different types of distortion and impairment. Some arise from the nature of IP - lost packets, packet jitter, seriously delayed packets, out of order packets. Others arise from codecs which are heavily optimised for speech, not modem tones. Consequently, fax transmission between analogue fax machines over VoIP has uncertain success.
T.38 was developed to address that but as I explained above it can only work if implemented at the necessay points in the end to end path. There is no compulsion for network operators and service providers to implement T.38. Outside of Japan, fax is small beer.
Having said all that, I do have a Brother MFC-J4510DW connected to my OBi110 (which does not have T.38) which I occasionally use to send faxes to Japan using Localphone (UK) as ITSP. Most times, but not always, transmission is successful.
The two phone ports of an OBi202 behave identically. It may be that the processor does not have enough grunt to run the T.38 processing on two fax calls taking place simultaneously. That is speculation on my part but I cannot think of any other reason for what you claim to have read. When T.38 is not in use an OBi treats a fax call in the same way as a voice call and an OBi202 is certainly capable of two simultaneous voice calls. You will not have an improved result by changing from an OBi200 to any other OBi model.
Regarding "GV and fax support", that to me does not mean that faxes are claimed to work if GV is the ITSP.
Sheffield_Steve:
I have a Obi200 and use Callcentric. My Canon MF247dw multi-function machine send faxes perfectly every time and has no changes to the default settings. I've never tried it with GVoice though
drgeoff:
Quote from: Sheffield_Steve on June 10, 2019, 08:04:39 am
I have a Obi200 and use Callcentric. My Canon MF247dw multi-function machine send faxes perfectly every time and has no changes to the default settings. I've never tried it with GVoice though
I was about to suggest that Thomike investigate other service providers who do support T.38. Callcentric is one of them - https://www.callcentric.com/faq/30#205 is worth reading.
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