[cisco-voip] Fwd: Cisco ATA Fax Confusion

[Nick Matthews]

passthrough and pass-through get you to the same place, just with two
different methods.

just like protocol based T38 and NSE based T38 get you to the same
place, just in two different ways.  The end destination is the same
for protocol based or NSE based.  I'm not entirely sure what your
question is.  What I'm saying is that there was a new project to make
that 'destination' or protocol be able to handle higher speeds.  At
the moment I can't remember if it was a 15.0M release or 15.1T
release.


-nick

On Sun, Jan 24, 2010 at 1:06 PM, Rhodium <rhodium_uk at yahoo.co.uk> wrote:
> In relation to Ryan's comments, it would be NSE based fax passthrough with the fax negotiating low speed, not something inherently differently to the passthrough protocol. So it is not a different type of FaxoIP method but uses an existing method which is NSE passthrough.
>
> Am I right?
>
> --- On Sun, 1/24/10, Nick Matthews <matthnick at gmail.com> wrote:
>
>> From: Nick Matthews <matthnick at gmail.com>
>> Subject: Re: [cisco-voip] Fwd: Cisco ATA Fax Confusion
>> To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> Cc: "Ryan Ratliff" <rratliff at cisco.com>, "cisco-voip at puck.nether.net Group" <cisco-voip at puck.nether.net>
>> Date: Sunday, January 24, 2010, 5:50 PM
>> both passthrough, pass-through, and
>> relay can handle up to 14.4.  Some
>> of the newer 15.0 code is supposed to allow 56k, but I
>> haven't heard
>> the results of the testing.
>>
>> -nick
>>
>> On Sun, Jan 24, 2010 at 9:41 AM, Rhodium <rhodium_uk at yahoo.co.uk>
>> wrote:
>> > Hi Nick,
>> >
>> > Thanks for replying.
>> >
>> > So low speed fax as mentioned by Ryan is just fax
>> "passthrough" (NSE based) with the fax negotiating a speed
>> of <=9600 bps.
>> >
>> > Regards,
>> >
>> > Jason
>> >
>> > --- On Sun, 1/24/10, Nick Matthews <matthnick at gmail.com>
>> wrote:
>> >
>> >> From: Nick Matthews <matthnick at gmail.com>
>> >> Subject: Re: [cisco-voip] Fwd: Cisco ATA Fax
>> Confusion
>> >> To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> Cc: "Ryan Ratliff" <rratliff at cisco.com>,
>> "cisco-voip at puck.nether.net
>> Group" <cisco-voip at puck.nether.net>
>> >> Date: Sunday, January 24, 2010, 5:50 AM
>> >> To clarify:
>> >>
>> >> fax pass-through:  protocol based pass through.
>> >> Supported in SIP/H323.
>> >> fax passthrough: nse based passthrough.  Same
>> thing as
>> >> modem passthrough
>> >> fax relay:  a method of turning g711 packets
>> into
>> >> specific fax
>> >> packets.  Options are T38 and Cisco.
>> >> Cisco fax relay:  The default method in IOS
>> versions
>> >> before 15.0, and
>> >> uses Cisco NSEs for transport and negotiation.
>> This
>> >> is not the
>> >> suggested option, as it is legacy.
>> >> T38 NSE switchover:  this is cisco proprietary,
>> and is
>> >> supported with
>> >> SCCP, SIP, MGCP, and H323
>> >> T38 protocol switchover:  This is standards based
>> and
>> >> what you will
>> >> use with 3rd party devices.  Supported in SIP,
>> H323,
>> >> and MGCP.
>> >> NSE:  A cisco proprietary packet value for RTP
>> >> (normally 101) that is
>> >> used between Cisco devices to signal certain fax
>> events.
>> >>
>> >> modem passthrough: used for both fax and modem
>> passthrough
>> >> using G711.
>> >>  Available in the 4 protocols.  Only thing that
>> ATAs
>> >> officially
>> >> support.  It turns off the echo canceller, and
>> changes
>> >> the playout
>> >> buffer (for jitter).  Cisco proprietary since it
>> uses
>> >> NSEs.
>> >>
>> >> Faxes can work on G711, but that is if the echo
>> canceller
>> >> and playout
>> >> buffer work for that particular stream and
>> associated fax
>> >> machines.
>> >> It's very likely that high speed faxes (speed >
>> 14.4)
>> >> will not work on
>> >> normal G711.
>> >>
>> >>
>> >> Faxing is confusing :)
>> >>
>> >> -nick
>> >>
>> >> On Fri, Jan 22, 2010 at 4:52 PM, Rhodium <rhodium_uk at yahoo.co.uk>
>> >> wrote:
>> >> > Can't find anything about that particular fax
>> oIP
>> >> method from googling or on CCO??
>> >> >
>> >> > All I can find are the relay types, and the
>> >> pass-through/passthrough types.
>> >> >
>> >> > Regards,
>> >> >
>> >> > Jason
>> >> >
>> >> > --- On Fri, 1/22/10, Ryan Ratliff <rratliff at cisco.com>
>> >> wrote:
>> >> >
>> >> >> From: Ryan Ratliff <rratliff at cisco.com>
>> >> >> Subject: Re: [cisco-voip] Fwd:  Cisco
>> ATA Fax
>> >> Confusion
>> >> >> To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> >> Cc: "cisco-voip at puck.nether.net
>> >> Group" <cisco-voip at puck..nether.net>
>> >> >> Date: Friday, January 22, 2010, 9:40 PM
>> >> >> It's basically the same as the
>> >> >> straight g.711 fax pass-through.  I
>> think the
>> >> only
>> >> >> difference with this and modem
>> passthrough is that
>> >> when we
>> >> >> detect the fax tones we'll turn off some
>> of the
>> >> DSP features
>> >> >> (ecan, etc) that are useful for voice but
>> not for
>> >> fax.
>> >> >>
>> >> >> -Ryan
>> >> >>
>> >> >> On Jan 22, 2010, at 4:34 PM, Rhodium
>> wrote:
>> >> >>
>> >> >> Thanks for following it up internally.
>> :)
>> >> >>
>> >> >> What is this by the way in terms of fax
>> >> protocols:
>> >> >>
>> >> >> > The other option is that it has
>> fallen back
>> >> to g.711
>> >> >> low
>> >> >> > speed fax and you are getting
>> lucky.
>> >> >>
>> >> >>
>> >> >> --- On Fri, 1/22/10, Ryan Ratliff <rratliff at cisco.com>
>> >> >> wrote:
>> >> >>
>> >> >> > From: Ryan Ratliff <rratliff at cisco.com>
>> >> >> > Subject: Re: [cisco-voip] Fwd:
>> Cisco ATA
>> >> Fax
>> >> >> Confusion
>> >> >> > To: "Rhodium" <rhodium_uk at yahoo.co.uk>
>> >> >> > Cc: "cisco-voip at puck.nether.net
>> >> >> Group" <cisco-voip at puck.nether.net>
>> >> >> > Date: Friday, January 22, 2010, 9:26
>> PM
>> >> >> > I ran this by somebody that
>> actually
>> >> >> > works fax issues every day and there
>> are two
>> >> ways your
>> >> >> call
>> >> >> > can be working.
>> >> >> >
>> >> >> > The first is that modem passthrough
>> is
>> >> actually being
>> >> >> > used.  This can be confirmed by
>> waiting 10
>> >> >> seconds
>> >> >> > after the call is answered and
>> looking at the
>> >> output
>> >> >> of
>> >> >> > 'show call active voice brief'.  If
>> you see
>> >> >> modem-pass
>> >> >> > here then it's switched to modem
>> >> passthrough.
>> >> >> >
>> >> >> > The other option is that it has
>> fallen back
>> >> to g.711
>> >> >> low
>> >> >> > speed fax and you are getting
>> lucky.
>> >> >> >
>> >> >> > -Ryan
>> >> >> >
>> >> >> > On Jan 22, 2010, at 4:15 PM, Ryan
>> Ratliff
>> >> wrote:
>> >> >> >
>> >> >> > Are your calls working in one
>> direction only
>> >> or both
>> >> >> > ways?  We are all in agreement that
>> the ATA
>> >> only
>> >> >> > supports NSE based passthrough and I
>> do know
>> >> that the
>> >> >> > default fax protocol on cisco
>> routers is
>> >> modem
>> >> >> passthrough
>> >> >> > so maybe there's another bit of your
>> config
>> >> that's
>> >> >> allowing
>> >> >> > the call to proceed.
>> >> >> >
>> >> >> > In the doc you referenced it
>> mentions that
>> >> no
>> >> >> fall-back
>> >> >> > will still allow for the fax to
>> proceed if
>> >> modem
>> >> >> passthrough
>> >> >> > is configured..  Maybe this also
>> applies if
>> >> fax
>> >> >> > pass-through fallback isn't
>> successful.
>> >> >> >
>> >> >> > -Ryan
>> >> >> >
>> >> >> > On Jan 22, 2010, at 3:50 PM, Rhodium
>> wrote:
>> >> >> >
>> >> >> > Yep, I am aware of the hyphenations.
>> Been
>> >> trying to
>> >> >> use
>> >> >> > them in the right context if you
>> look at my
>> >> emails.
>> >> >> ;o)
>> >> >> >
>> >> >> > I don't think the fall back command
>> applies
>> >> to NSE
>> >> >> > passthrough but protocol based
>> pass-through:
>> >> >> >
>> >> >> > http://www.cisco..biz/en/US/docs/ios/12_3/vvf_c/cisco_ios_fax_services_over_ip_application_guide/t38.html#wp1156682
>> >> >> >
>> >> >> > Also, the written documentation I
>> have shows
>> >> it under
>> >> >> > protocol based pass-through.
>> >> >> >
>> >> >> > Which led me to ask the question,
>> why is it
>> >> working?
>> >> >> Are
>> >> >> > you sure that it refers to protocol
>> based
>> >> pass-through
>> >> >> and
>> >> >> > not NSE?
>> >> >> >
>> >> >> > Regards,
>> >> >> >
>> >> >> > Jason
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> _______________________________________________
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>> >> >> > cisco-voip at puck.nether.net
>> >> >> > https://puck.nether.net/mailman/listinfo/cisco-voip
>> >> >> >
>> >> >> >
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >>
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
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>> >> >
>> >>
>> >
>> >
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