Re: V17 vs V34, MSANs and faxanswer
Christo Labuschagne <[email protected]> Mon, 11 Jun 2018 08:12:02 +0200
| Newsgroups | gmane.comp.telephony.fax.hylafax.user |
|---|---|
| Message-ID | <CALPXzFgE_sQd9SgugKntCNBL-82gLM=LGq28mZQN9aeC0r5Avg@mail.gmail.com> |
--000000000000d137a2056e57a0b8 Content-Type: text/plain; charset="UTF-8" Hi Shouldbe On Sat, Jun 9, 2018 at 1:24 PM, shouldbe q931 <[email protected]> wrote: > On Wed, Jun 6, 2018 at 11:30 AM, Christo Labuschagne > <[email protected]> wrote: > > Good day all > > > > We have a problem on a line (that is very far away and not manned by a > > specialist) where sending a fax works fine but we cannot receive a fax. > It > > answers but does not want to train or trains at 2400 and then no data > gets > > through. A V17 fax machine works fine though. After a lot of studying > of > > how network infrastructure works, we have learned that networks use CED > or > > /ANSam to open up the channel with either T.38/G711 for CED or G711 for > > /ANSam. > > Do you guys have any idea if this is correct? > > > My experience is by no means exhaustive, but I jhave not experienced a > telco that does tone detection on calls, I have seen "fax splitters" > that do tone detection so a fax machine and a telephone can share a > line. > Sorry, this is just a repeat of my mail to Lee. Just added here for completeness. 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. > > > > > If it is correct, have you ever had lines that does not support /ANSam? > > > > The same modem can be connected to various interfaces, so in some cases > we > > would like to answer with V17 (PSTN) and in other cases V34 (PABX). > > faxanswer does not have an option to specify a speed limit like sendfax > has > > with -B. The only way I could limit the answering fax modem to answer > with > > CED is to remove the Class1EnableV34Cmd from the config. > > Is there a way to configure the answering mode (CED or ANSam) on the fly? > > I don;t follow what you mean by "interfaces" in this sense, and also > do not follow why you have ascribed V17 to PSTN and V34 to PABX > Our fax modem can connect to either a SLIC or a DAA. When connected to a SLIC we can import directly from a fax (we are then the "Telco"). When connected to the DAA, we send a fax to another fax or one of our devices over the countries telco. > > https://en.wikipedia.org/wiki/List_of_ITU-T_V-series_recommendations > > What model modem is this ? > I think your question here is what is the capabilities of the modem? Capable of doing both V.34 fax and V.17 fax. > > > > I'm trying to get as much info ready before we go out and try and fix the > > problem. > > > > Running Linux btw. > > > > The one option I have is to create a symbolic link to the same modem and > > then have two config files. I could then start the same modem up > depending > > on the interface and then just call faxanswer with the correct modem, but > > this would cause a modem reboot for at least one interface (idle in V34 > mode > > and then stop hylafax for that mode and then start it for V17 mode if a > call > > comes in on a different interface). Not elegant, but an option. > > > > Thanks again for a great product! > > > > Kind regards > > Christo > > > ____________________ HylaFAX(tm) Users Mailing List _______________________ > To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-b > in/lsg2.cgi > On UNIX: mail -s unsubscribe [email protected] < > /dev/null > *To learn about commercial HylaFAX(tm) support, mail [email protected].* > > --000000000000d137a2056e57a0b8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">Hi Shouldbe<br><div class=3D"gmail_extra"><br><div class= =3D"gmail_quote">On Sat, Jun 9, 2018 at 1:24 PM, shouldbe q931 <span dir=3D= "ltr"><<a href=3D"mailto:[email protected]" target=3D"_blank">shoul= [email protected]</a>></span> wrote:<br><blockquote class=3D"gmail_quote= " style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><= span>On Wed, Jun 6, 2018 at 11:30 AM, Christo Labuschagne<br> <<a href=3D"mailto:[email protected]" target=3D"_blank">fc.labusc= [email protected]</a>> wrote:<br> > Good day all<br> ><br> > We have a problem on a line (that is very far away and not manned by a= <br> > specialist) where sending a fax works fine but we cannot receive a fax= .=C2=A0 It<br> > answers but does not want to train or trains at 2400 and then no data = gets<br> > through.=C2=A0 A V17 fax machine works fine though.=C2=A0 After a lot = of studying of<br> > how network infrastructure works, we have learned that networks use CE= D or<br> > /ANSam to open up the channel with either T.38/G711 for CED or G711 fo= r<br> > /ANSam.<br> > Do you guys have any idea if this is correct?<br> <br> <br> </span>My experience is by no means exhaustive, but I jhave not experienced= a<br> telco that does tone detection on calls, I have seen "fax splitters&qu= ot;<br> that do tone detection so a fax machine and a telephone can share a<br> line.<br></blockquote><div><br></div><div>Sorry, this is just a repeat of m= y mail to Lee.=C2=A0 Just added here for completeness.</div><div>What I hav= e read online is that MSAN's would use the CED to enable T.38 between M= SAN's or (in the case of /ANSam use G.711) and disable the echo cancele= rs (EC) and voice activity detectors (VAD)<br></div><div><div style=3D"font= -size:small;background-color:rgb(255,255,255);text-decoration-style:initial= ;text-decoration-color:initial"><br></div><div style=3D"font-size:small;bac= kground-color:rgb(255,255,255);text-decoration-style:initial;text-decoratio= n-color:initial">Please refer to this site:</div><div style=3D"font-size:sm= all;background-color:rgb(255,255,255);text-decoration-style:initial;text-de= coration-color:initial"><br></div><div style=3D"font-size:small;background-= color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:= initial"><a href=3D"http://what-when-how.com/voip/fax-basic-functionality-a= nd-detecting-fax-call-voip/" target=3D"_blank">http://what-when-how.com/voi= p/<wbr>fax-basic-functionality-and-<wbr>detecting-fax-call-voip/</a><br></d= iv><div style=3D"font-size:small;background-color:rgb(255,255,255);text-dec= oration-style:initial;text-decoration-color:initial"><br></div><div style= =3D"font-size:small;background-color:rgb(255,255,255);text-decoration-style= :initial;text-decoration-color:initial"><span style=3D"color:rgb(17,17,17);= font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size= :16px;background-color:rgb(255,255,255);text-decoration-style:initial;text-= decoration-color:initial;float:none;display: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 generated by the fax terminal are sent a= s 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 s= witches to a T.38 fax call or fax pass-through call based on the gateway ca= pability negotiations.</span><span>=C2=A0</span><br></div><div style=3D"fon= t-size:small;background-color:rgb(255,255,255);text-decoration-style:initia= l;text-decoration-color:initial"><br></div><div style=3D"font-size:small;ba= ckground-color:rgb(255,255,255);text-decoration-style:initial;text-decorati= on-color:initial">and this:</div><div style=3D"font-size:small;background-c= olor:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:i= nitial"><br></div><div style=3D"font-size:small;background-color:rgb(255,25= 5,255);text-decoration-style:initial;text-decoration-color:initial"><a href= =3D"http://what-when-how.com/voip/fax-and-modem-tones-basics-voip/" target= =3D"_blank">http://what-when-how.com/voip/<wbr>fax-and-modem-tones-basics-<= wbr>voip/</a><br></div><div style=3D"font-size:small;background-color:rgb(2= 55,255,255);text-decoration-style:initial;text-decoration-color:initial"><b= r></div><div style=3D"font-size:small;background-color:rgb(255,255,255);tex= t-decoration-style:initial;text-decoration-color:initial"><span style=3D"co= lor:rgb(17,17,17);font-family:Arial,"Helvetica Neue",Helvetica,sa= ns-serif;font-size:16px;background-color:rgb(255,255,255);text-decoration-s= tyle:initial;text-decoration-color:initial;float:none;display:inline">With = CED detection, echo canceller nonlinear processing (NLP) is disabled and ba= sic echo adaptation is kept in the enabled mode.</span><span>=C2=A0</span><= br></div><br class=3D"m_5801374745418449399gmail-Apple-interchange-newline"= > <br></div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margi= n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <span><br> ><br> > If it is correct, have you ever had lines that does not support /ANSam= ?<br> ><br> > The same modem can be connected to various interfaces, so in some case= s we<br> > would like to answer with V17 (PSTN) and in other cases V34 (PABX).<br= > > faxanswer does not have an option to specify a speed limit like sendfa= x has<br> > with -B.=C2=A0 The only way I could limit the answering fax modem to a= nswer with<br> > CED is to remove the Class1EnableV34Cmd from the config.<br> > Is there a way to configure the answering mode (CED or ANSam) on the f= ly?<br> <br> </span>I don;t follow what you mean by "interfaces" in this sense= , and also<br> do not follow why you have ascribed V17 to PSTN and V34 to PABX<br></blockq= uote><div><br></div><div>Our fax modem can connect to either a SLIC or a DA= A.=C2=A0 When connected to a SLIC we can import directly from a fax (we are= then the "Telco").=C2=A0 When connected to the DAA, we send a fa= x to another fax or one of our devices over the countries telco.=C2=A0=C2= =A0</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin= :0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <br> <a href=3D"https://en.wikipedia.org/wiki/List_of_ITU-T_V-series_recommendat= ions" rel=3D"noreferrer" target=3D"_blank">https://en.wikipedia.org/wiki/<w= br>List_of_ITU-T_V-series_recomme<wbr>ndations</a><br> <br> What model modem is this ?<br></blockquote><div><br></div><div>I think your= question here is what is the capabilities of the modem?=C2=A0 Capable of d= oing both V.34 fax and V.17 fax.=C2=A0=C2=A0</div><div><br></div><blockquot= e class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc sol= id;padding-left:1ex"> <span><br> ><br> > I'm trying to get as much info ready before we go out and try and = fix the<br> > problem.<br> ><br> > Running Linux btw.<br> ><br> > The one option I have is to create a symbolic link to the same modem a= nd<br> > then have two config files.=C2=A0 I could then start the same modem up= depending<br> > on the interface and then just call faxanswer with the correct modem, = but<br> > this would cause a modem reboot for at least one interface (idle in V3= 4 mode<br> > and then stop hylafax for that mode and then start it for V17 mode if = a call<br> > comes in on a different interface).=C2=A0 Not elegant, but an option.<= br> ><br> > Thanks again for a great product!<br> ><br> > Kind regards<br> > Christo<br> <br> <br> </span>____________________ HylaFAX(tm) Users Mailing List ________________= _______<br> =C2=A0 To subscribe/unsubscribe, click <a href=3D"http://lists.hylafax.org/= cgi-bin/lsg2.cgi" rel=3D"noreferrer" target=3D"_blank">http://lists.hylafax= .org/cgi-b<wbr>in/lsg2.cgi</a><br> =C2=A0On UNIX: mail -s unsubscribe <a href=3D"mailto:hylafax-users-request@= hylafax.org" target=3D"_blank">hylafax-users-request@hylafax.<wbr>org</a> &= lt; /dev/null<br> =C2=A0 *To learn about commercial HylaFAX(tm) support, mail [email protected].= *<br> <br> </blockquote></div><br></div></div> --000000000000d137a2056e57a0b8-- ____________________ 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].*