Sorry to butt in here. I know a bit about VoIP, but not much about Fax over IP. I'd be curious to know why Error Correction (ECO ??) doesn't work when the data stream is routed via IP. I assume we're talking about POTS fax machines connected via an FXS->IP gateway? Or are these actual IP fax machines?
Regards, Keith. Matt Keys wrote: > Thanks for the information Todd and Jan. I'll pay closer attention to > the fax machine itself. > > The successful test was performed using a SPA-2102 running version > 3.3.6 firmware, hardware version 1.2.5a. The fax models were a > Panasonic KX-FL511 and a Ricoh Aficio 3030 on the other--Both are G3. > > The failed test was using AudioCodes MP-112 running version 5 > firmware. I used a Brother MFC-8220 on one end and the same Panasonic > KX-FL511 on the other. I also tried the HP test fax number I mentioned > earlier--I'm not sure what they use on their end. Outbound I could > hear the fax tone for about 2 seconds and then it went silent. Inbound > (Panasonic to Brother) the fax went through. > > > -----Original Message----- > From: [email protected] on behalf of Todd Hodgen > Sent: Thu 6/11/2009 3:00 AM > To: 'Jan Schumacher'; [email protected] > Subject: Re: [sipx-users] fax compatibility list? > > Sorry, Fat fingered that one. G3. I've had instances with some fax > machines that receive a call from a like machine and they determine that > they are Super G3 compatible, they turn ECO back on when it is turned off. > I think it's a Panasonic if I'm not mistaken. You think everything is > working fine, and then intermittently, you get faxes that don't work. You > scramble around playing with gateways, etc. to find it was a fax > machine all > along. It's that Super G3 tone that is being manhandled by one ITSP to > improve their fax service over their IP network. It's a real problem for > the ITSP's, although many don't admit it, while others openly say it's a > problem. > > I've not ran into T.38 redundancy. It's been a while since I read the > spec's on T.38, but from what I remember, T.38 since it has no error > correction, transmits each packet multiple times as its form of > ensuring the > data gets to the other side. If my memory serves me, what I remember > reading is that the standard doesn't say how many times to transmit > it, that > it's up to the sender to determine how many times to transmit the data. I > did a quick google on T.38 redundancy and Cisco was saying in their > configuration that it determines the number of times the data is > transmitted. It didn't go into great detail, but lead me to believe that > they allow theirs to be configurable maybe? > > I'm by no means an expert on this subject, I just have a few more grey > hairs > from it having fought issues from it with some larger customers. > > Sometimes it's to easy to point a finger at something we don't understand, > when the real issue is really another component on the network. I'm only > suggesting people not ignore that their fax issues could actually be > the fax > machines and their inability to play within the constrictions of > T.38. And, > it's a really easy thing to check out. One big key, if you get one > page and > then it drops each time, check ECO. > > -----Original Message----- > From: Jan Schumacher [mailto:[email protected]] > Sent: Wednesday, June 10, 2009 11:36 PM > To: [email protected]; [email protected] > Subject: Re: [sipx-users] fax compatibility list? > > Hi Todd, > > what did you mean with G5 fax machine? Is it a T.38 IP fax machine? > Is it better to turn off the T.38 redundancy too? > > Jan > > 2009/6/11 Todd Hodgen <[email protected]>: > > Are you sure the issue is with the Gateway itself and not the fax > machines. > > It's important on the faxes to turn off Error Correction. And, it gets > > trickey, because some machines allow you to turn them off, some require > the > > manufacturer to turn them off, and some turn back on by themselves when > they > > detect a G5 fax machine. Error Correction must be turned off for Faxing > to > > work in an IP network. I learned this lesson the hard way with some > large > > Nortel CS1000 implementations. Problem wasn't the switch, but the fax > > machines on the ends, and the T.38 protocol itself. > > > > I know of at least one ITSP's that's even beginning to tweak their > network > > now to ensure error correction is stripped off of their network entirely > to > > improve fax capabilities. > > > > Voipfrustration.com is a sight that has instructions for turning off > Error > > Correction on different Fax Machines, it can be helpful when things are > > coming together. > > > > > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of Matt Keys > > Sent: Wednesday, June 10, 2009 9:42 PM > > To: [email protected] > > Subject: [sipx-users] fax compatibility list? > > > > Is there a list of sipxecs tested/certified ATAs that work for faxing? I > > was able to get a SPA-2102 to send/receive yesterday. Tests using a > > AudioCodes MP-112 (version 5 firmware) have failed. > > > > FYI - I just discovered HP has a very handy tool available. Call > > 1-888-hpfaxme (1-888-473-2963) and it will receive your test fax and > > send it back to you. See > > > http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00259105&lc=en&dlc=&cc= > <http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00259105&lc=en&dlc=&cc=> > > us&product=424230 . > > > > > > _______________________________________________ > > sipx-users mailing list [email protected] > > List Archive: http://list.sipfoundry.org/archive/sipx-users > > Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users > > sipXecs IP PBX -- http://www.sipfoundry.org/ > > > > _______________________________________________ > > sipx-users mailing list [email protected] > > List Archive: http://list.sipfoundry.org/archive/sipx-users > > Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users > > sipXecs IP PBX -- http://www.sipfoundry.org/ > > > > _______________________________________________ > sipx-users mailing list [email protected] > List Archive: http://list.sipfoundry.org/archive/sipx-users > Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users > sipXecs IP PBX -- http://www.sipfoundry.org/ > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.339 / Virus Database: 270.12.50/2150 - Release Date: > 06/10/09 05:52:00 > >------------------------------------------------------------------------ > >_______________________________________________ >sipx-users mailing list [email protected] >List Archive: http://list.sipfoundry.org/archive/sipx-users >Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users >sipXecs IP PBX -- http://www.sipfoundry.org/ > >------------------------------------------------------------------------ > > >No virus found in this incoming message. >Checked by AVG - www.avg.com >Version: 8.5.364 / Virus Database: 270.12.62/2168 - Release Date: 06/10/09 >18:30:00 > > > _______________________________________________ sipx-users mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-users Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users sipXecs IP PBX -- http://www.sipfoundry.org/
