ISDN CHANNEL-D

ISDN CHANNEL-D

[AstinusLists]

Hello every one.

I've been earing some rumors, that i am quite sure that are turth about the
isdn channel d.

As all of u know ( i think ) isdn cards have 3 channels: 2*64 and one time
16 kbs.

This last one is called channel D.
Channel D is used to dial and to reply to tones and minor stuff like that.

The big deal here in my country is that u don't have to pay for the channel
D traffic ( And it is legal to use it, i can assure that, cause i am well
informed on that matter!)

Many banks use the channel D to money transfers and so.
But in order to do that they had to aquire some hard and software that all
together costs arround 500 US Dollars or 450 Euros more or less.

K this was just an intro! The interesting part is that some students from
www.ist.pt ( TECNICO), managed to build some software that allows to use the
ISDN Channel d without any  need of additional hardware.....

I would like to know if any of u isdn driver hackers can point me out a way
of how to build such a program or where to read some real good stuff about
this ISDN-D channel.

Regards, Astinus

Re: ISDN CHANNEL-D

[Kristian]

"AstinusLists" <AstinusLists@netcabo.pt> wrote:
> [..]
> I would like to know if any of u isdn driver hackers can point me out a way
> of how to build such a program or where to read some real good stuff about
> this ISDN-D channel.

If you're looking for drivers, please go to isdn4linux.de (or search for newsgroups that have "isdn4linux" in their title). As far as I know the current hisax drivers (which are included in the kernel as well) support d-channel. But the d channel is only meant for starting a connection, not to support whole traffic. And it is rather slow. So it would make no fun compared to 64kbs...
I can provide you an email address of one linux-guy from AVM. This (german) company is responsible for many active isdn cards and I think their drivers are supporting d-channel too.

*Kristian

·· · · reach me :: · ·· ·· ·  · ·· · ··  · ··· · ·
                         :: http://www.korseby.net
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kristian@korseby.net ....::

Re: ISDN CHANNEL-D

[Rene Rebe]

Hi ;-)

From: Kristian <kristian.peters@korseby.net>
Subject: Re: ISDN CHANNEL-D
Date: Wed, 16 Jan 2002 21:21:22 +0100

> "AstinusLists" <AstinusLists@netcabo.pt> wrote:
> > [..]
> > I would like to know if any of u isdn driver hackers can point me out a way
> > of how to build such a program or where to read some real good stuff about
> > this ISDN-D channel.
> 
> If you're looking for drivers, please go to isdn4linux.de (or search for newsgroups that have "isdn4linux" in their title). As far as I know the current hisax drivers (which are included in the kernel as well) support d-channel. But the d channel is only meant for starting a connection, not to support whole traffic. And it is rather slow. So it would make no fun compared to 64kbs

They support real traffic. The Telekom (here in Germany) used it for a
free (in addition to the normal IDSN internet access ...) "continously
connected" service. For email and chat. It was only a test and never
spread widely ...

[...]

k33p h4ck1n6
  René

-- 
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Re: ISDN CHANNEL-D

[Padraig Brady]

AstinusLists wrote:

> Hello every one.
> 
> I've been earing some rumors, that i am quite sure that are turth about the
> isdn channel d.
> 
> As all of u know ( i think ) isdn cards have 3 channels: 2*64 and one time
> 16 kbs.
> 
> This last one is called channel D.
> Channel D is used to dial and to reply to tones and minor stuff like that.
> 
> The big deal here in my country is that u don't have to pay for the channel
> D traffic ( And it is legal to use it, i can assure that, cause i am well
> informed on that matter!)


Yes info is passed across the D channel in messages. There is a message

type called User User information that can be passed, but only with and
associated D channel call type, i.e. you must pay for it.

Also other "standard" messages like "call setup", "progress", ... can
contain user user info, but these can only be transfer after the call
is established.

In both cases an explicit call must be established first, so you're
billed for such traffic.

Now I suppose you could set specific bits in standard call setup 
messages for e.g. that could be used to transfer info between
users, but I'd say about 10bits max per call setup? which is not
interesting.

Search the net for Q931 for ISDN D channel protocol spec.

What does this have to do with Linux again?


Padraig.

Re: ISDN CHANNEL-D

[Sam Ravnborg]

On Wed, Jan 16, 2002 at 08:58:02PM +0000, Padraig Brady wrote:
> AstinusLists wrote:
> 
> > Hello every one.
> > 
> > I've been earing some rumors, that i am quite sure that are turth about the
> > isdn channel d.
> > 
> > As all of u know ( i think ) isdn cards have 3 channels: 2*64 and one time
> > 16 kbs.
> > 
> > This last one is called channel D.
> > Channel D is used to dial and to reply to tones and minor stuff like that.
> 
> Yes info is passed across the D channel in messages. There is a message
> 
> type called User User information that can be passed, but only with and
> associated D channel call type, i.e. you must pay for it.

What the original author refer to is utilising the D-Channel to support
LAPB/X.25 traffic. This is done using a special SAPI=16 value.
I dunno if the ISDN drivers in Linux support this yet.

Charging for the above is operator specific, when I worked with this in the past
the charging was unrealistic high.

	Sam