Re: V17 vs V34, MSANs and faxanswer
Christo Labuschagne <[email protected]> Mon, 11 Jun 2018 08:01:12 +0200
| Newsgroups | gmane.comp.telephony.fax.hylafax.user |
|---|---|
| Message-ID | <CALPXzFiX_dL4Ysm3EdjrztRZwosvripu-p1fyTiVLfuC6dMz_g@mail.gmail.com> |
--000000000000154dbe056e577aa7 Content-Type: text/plain; charset="UTF-8" Hi Lee On Fri, Jun 8, 2018 at 11:10 PM, Lee Howard <[email protected]> wrote: > On 06/08/2018 12:48 AM, Christo Labuschagne wrote: > > Files attached show the two different failures I saw. c00000006 is the > one I saw most. c000000013 I only saw once. > > > They look like poor line audio quality issues... typical stuff for VoIP > lines. > What does this mean? Do they use codecs not optimal for fax like G729 or G722? Is there something wrong with the copper (don't think its a copper issue as other products work fine and a V34 call is possible in the other direction)? Our question is mainly why would our product struggle (not activate the correct switches on the MSAN) but other fax machines work? > > > Not sure in which countries you still get end to end copper PSTN lines. I > think almost all run a VoIP backbone? Believe me, not my first choice! > > > PSTN does not have to be copper end-to-end. For much of it there will be > fiber, and it will be digital rather than analog, too. It's just a > different network - designed to ensure first-in-first-out service. That's > quite distinct from the jittery IP internet. > This is something I have not heard of. How would the MSAN's know how to enable this over a jittery voice protocol? What I have read online is that MSAN's would use the CED to enable T.38 between MSAN's or (in the case of /ANSam use G.711) and disable the echo cancelers (EC) and voice activity detectors (VAD) Please refer to this site: http://what-when-how.com/voip/fax-basic-functionality-and-detecting-fax-call-voip/ CNG tone, CED or ANS, /ANSam, and V.21 preamble tones are used as in-band packets passing through a voice call. The call setup tones generated by the fax terminal are sent as in-band (RTP) payload using preferred voice codecs such as G.711, G.729AB, G.723.1A, and G.726. The codecs G.729AB and G.723.1A compressed tones are also found to be accepted by the fax machines and tone detectors. When the CED or / ANSam or V.21 preamble indication is detected, the VoIP gateway switches to a T.38 fax call or fax pass-through call based on the gateway capability negotiations. and this: http://what-when-how.com/voip/fax-and-modem-tones-basics-voip/ With CED detection, echo canceller nonlinear processing (NLP) is disabled and basic echo adaptation is kept in the enabled mode. > > DynamicConfig seems to be used after modem setup. AT+F34 is the command > used to setup V34 capabilities for the device. This will already have been > called during modem setup before DynamicConfig gets called, correct? This > seems to cause the next call to use the Class1EnableV34Cmd and not the > current call > > > So, you'd use DynamicConfig (adjusting ModemAnswerCmd) to disable what was > enabled previously. Something like: > > ModemAnswerCmd: "AT+FCLASS=1;A" > Cool, I'll give this a go. > > That said, I don't think that ANSam is your problem. > That is unfortunate. I was hope that the MSAN would not detect the ANSam but would detect the CED... > > What kind of modem are you using? > Davicom DM6588A > > Thanks, > > Lee. > Christo --000000000000154dbe056e577aa7 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">Hi Lee<br><div class=3D"gmail_extra"><br><div class=3D"gma= il_quote">On Fri, Jun 8, 2018 at 11:10 PM, Lee Howard <span dir=3D"ltr"><= ;<a href=3D"mailto:[email protected]" target=3D"_blank">faxguy@howard= silvan.com</a>></span> wrote:<br><blockquote class=3D"gmail_quote" style= =3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding= -left:1ex"> =20 =20 =20 <div bgcolor=3D"#FFFFFF"><span class=3D"gmail-"> <div class=3D"gmail-m_-8429795715028466816moz-cite-prefix">On 06/08/201= 8 12:48 AM, Christo Labuschagne wrote:<br> </div> <blockquote type=3D"cite"> <div dir=3D"ltr"> <div> <div class=3D"gmail_extra"> <div class=3D"gmail_quote">Files attached show the two different failures I saw.=C2=A0 c00000006 is the one I saw most.=C2=A0 c000000013 I only saw once.</div> </div> </div> </div> </blockquote> <br></span> They look like poor line audio quality issues... typical stuff for VoIP lines.</div></blockquote><div><br></div><div>What does this mean?= =C2=A0 Do they use codecs not optimal for fax like G729 or G722?=C2=A0 Is t= here something wrong with the copper (don't think its a copper issue as= other products work fine and a V34 call is possible in the other direction= )?=C2=A0 Our question is mainly why would our product struggle (not activat= e the correct switches on the MSAN) but other fax machines work?</div><bloc= kquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:= 1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor=3D"#FFFFFF"><span= class=3D"gmail-"><br> <br> <blockquote type=3D"cite"> <div dir=3D"ltr"> <div> <div class=3D"gmail_extra"> <div class=3D"gmail_quote">Not sure in which countries you still get end to end copper PSTN lines.=C2=A0 I think almost all run a VoIP backbone?=C2=A0 Believe me, not my first choic= e!</div> </div> </div> </div> </blockquote> <br></span> PSTN does not have to be copper end-to-end.=C2=A0 For much of it there will be fiber, and it will be digital rather than analog, too.=C2=A0 It= 's just a different network - designed to ensure first-in-first-out service.=C2=A0 That's quite distinct from the jittery IP internet.<= /div></blockquote><div><br></div><div>This is something I have not heard of= .=C2=A0 How would the MSAN's know how to enable this over a jittery voi= ce protocol?=C2=A0 What I have read online is that MSAN's would use the= CED to enable T.38 between MSAN's or (in the case of /ANSam use G.711)= and disable the echo cancelers (EC) and voice activity detectors (VAD)</di= v><div><br></div><div>Please refer to this site:</div><div><br></div><div><= a href=3D"http://what-when-how.com/voip/fax-basic-functionality-and-detecti= ng-fax-call-voip/">http://what-when-how.com/voip/fax-basic-functionality-an= d-detecting-fax-call-voip/</a><br></div><div><br></div><div> <span style=3D"color:rgb(17,17,17);font-family:Arial,"Helvetica Neue&q= uot;,Helvetica,sans-serif;font-size:16px;background-color:rgb(255,255,255);= text-decoration-style:initial;text-decoration-color:initial;float:none;disp= lay:inline">CNG tone, CED or ANS, /ANSam, and V.21 preamble tones are used = as in-band packets passing through a voice call. The call setup tones gener= ated by the fax terminal are sent as in-band (RTP) payload using preferred = voice codecs such as G.711, G.729AB, G.723.1A, and G.726. The codecs G.729A= B and G.723.1A compressed tones are also found to be accepted by the fax ma= chines and tone detectors. When the CED or / ANSam or V.21 preamble indicat= ion is detected, the VoIP gateway switches to a T.38 fax call or fax pass-t= hrough call based on the gateway capability negotiations.</span> <br></div><div><br></div><div>and this:</div><div><br></div><div><a href=3D= "http://what-when-how.com/voip/fax-and-modem-tones-basics-voip/">http://wha= t-when-how.com/voip/fax-and-modem-tones-basics-voip/</a><br></div><div><br>= </div><div> <span style=3D"color:rgb(17,17,17);font-family:Arial,"Helvetica Neue&q= uot;,Helvetica,sans-serif;font-size:16px;background-color:rgb(255,255,255);= text-decoration-style:initial;text-decoration-color:initial;float:none;disp= lay:inline">With CED detection, echo canceller nonlinear processing (NLP) i= s disabled and basic echo adaptation is kept in the enabled mode.</span> <br></div><div><br></div><blockquote class=3D"gmail_quote" style=3D"margin:= 0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">= <div bgcolor=3D"#FFFFFF"><span class=3D"gmail-"><br> <br> <blockquote type=3D"cite"> <div dir=3D"ltr"> <div> <div class=3D"gmail_extra"> <div class=3D"gmail_quote">DynamicConfig seems to be used after modem setup.=C2=A0 AT+F34 is the command used to setup V34 capabilities for the device.=C2=A0 This will already have been called during modem setup before DynamicConfig gets called, correct?=C2=A0 This seems to cause the next call to u= se the Class1EnableV34Cmd and not the current call</div> </div> </div> </div> </blockquote> <br></span> So, you'd use DynamicConfig (adjusting ModemAnswerCmd) to disable what was enabled previously.=C2=A0 Something like:<br> <br> ModemAnswerCmd: "AT+FCLASS=3D1;A"<br></div></blockquote><div>= <br></div><div>Cool, I'll give this a go.</div><div>=C2=A0</div><blockq= uote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1p= x solid rgb(204,204,204);padding-left:1ex"><div bgcolor=3D"#FFFFFF"> <br> That said, I don't think that ANSam is your problem.<br></div></blo= ckquote><div><br></div><div>That is unfortunate.=C2=A0 I was hope that the = MSAN would not detect the ANSam but would detect the CED...=C2=A0</div><blo= ckquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left= :1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor=3D"#FFFFFF"> <br> What kind of modem are you using?<br></div></blockquote><div><br></div>= <div>Davicom=C2=A0DM6588A</div><blockquote class=3D"gmail_quote" style=3D"m= argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left= :1ex"><div bgcolor=3D"#FFFFFF"> <br> Thanks,<br> <br> Lee.<br> </div> </blockquote></div><br></div><div class=3D"gmail_extra">Christo</div></div> --000000000000154dbe056e577aa7-- ____________________ HylaFAX(tm) Users Mailing List _______________________ To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-bin/lsg2.cgi On UNIX: mail -s unsubscribe [email protected] < /dev/null *To learn about commercial HylaFAX(tm) support, mail [email protected].*