[Asterisk-Dev] best approach for a new isdn driver mainly for asterisk.. ?!

[Steven Critchfield]

Quick question, Have you had good experience with USB devices under
linux that push fair amounts of data? I ask this since I haven't. This
list also shows that the USB stuff Mark has already been working with
seems to be finicky about which chipset is under it. I suggest you
double think the use of USB as a server level technology.

Don't take what I said before as a dismissal of your ideas, just a worry
that you would end up with a lot of time invested in a product that may
not be very stable due to parts outside of your project.

I do like the idea of seeing if the current ISDN adapters could be made
to be more of a raw device and then link the libpri functions in a
modified form for BRI to those devices. At that point a zap like
interface to ISDN hardware should be easy. Who kows, maybe we could get
to the point of supporting ISDN handsets which should be better than
ADSI. 

On Tue, 2003-04-22 at 08:54, Andrea Venturi wrote:
> hi,
> 
> we'd like to set up an asterisk server on a lightweight x86 pc with only 
> USB port.
> 
> we found this cheap isdn adapter: winbond w6694a
> 
>    http://www.winbond.com/PDF/sheet/W6694a.pdf
> 
> this seems an actually unsupported by linux usb adapter but it seems 
> *bsd supports it 8-)
> 
>    http://home.c2i.net/hselasky/isdn4bsd/privat/temporary/
> 
> it's passive card so not a plain ACM compatable!
> 
> the datasheet seems quite complete WRT register description so i think 
> it should be not a though task to try to support this card _but_ i have 
> a concern.
> 
> actually there are at least three (or four) environment WRT isdn on linux
> 
> 1- the classical isdn4linux effort (the hisax stack) but it's quite poor 
> WRT ISDN signaling if you use the /dev/ttyI* interface and "TE" mode only.
> 
> 2- the newer capi approach (i heard it should be the default in kernel 
> 2.5.x and onward but i don't know if it's true today)
> 
> 3- the zaptel/libpri way: do you think it could be easy to leverage the 
> tormenta skeleton? is the ISDN PRI signaling really the same ISDN Q931 
> (the D protocol on the BRI signaling channel in euro-land..): i see that 
> there's just a different module for the E400P and the E100P.. support 
> this new ISDN card could be just as easy as develop this low-level module ?
> 
> 4- the isdn raw device from http://isdn.jolly.de/ : i know this is not a 
> well known and developed kernel support but this has the advantage that 
> you can have both NT & TE support for the hfc based card.
> 
> IMHO the best approach could be number three (kudos to mark and co.) 
> because:
> 
> - it's fully GPL
> - it's reliable and running _now_ (when will have a capi kernel support 
> uncluttered !?)
> - it's feature-full (and not poor like the /dev/ttyI* emulation)
> - it's both voice & data ready
> - it's both NT & TE (in PRI level this is a quite light difference.. 
> maybe a PITA in the BRI level..)
> 
> on the other end, it's not a well known environment outside the asterisk 
> community so it's quite a challenge WRT well established "telco" driver 
> in linux world..
> 
> what do you think about the topic ?!
> 
> bye
> 
> andrea venturi
> 
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-- 
Steven Critchfield  <critch at basesys.com>