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

[George Bean]

> > > lastly, if you want to do this on a budget, used channel banks and
bri
> > > cards are pretty cheap. I recently bought a Premisys cb and six 8
port
> > > bri-u cards on ebay and haven't yet spent $200.
> > >
> >
> > Are you sure the BRI ports on those channel bank cards have an
aggregate
> > D channels on a single time slot of the attached T1? Most American
made
> > BRI cards are for the BRITE system that is used to transport ISDN
> > circuits from a switch site to a distant point, closer to the
customer
> > termination. They put D channels from 1-4 ISDN circuits on a T1 time
> > slot and thus use multiple time slots for D channel information.
> > Asterisk can only handle D channel information on a T1 when it is in
the
> > form of a PRI with a single aggregate D channel.
> 
> Check the archives, we have discussed the signalling before. If you
also
> go back in the thread, you will find that it is more likely that we
can
> get ISDN over T1 working than get network side signalling on a passive
> card.
> --
> Steven Critchfield <critch at basesys.com>

I am well aware of this thread and have been following it since its
inception as I do with all ISDN related threads. I spent several years
coordinating ISDN services for a major institution and along the way
collected several pieces of ISDN hardware that I would like to connect
to the PSTN with a cost effective switching solution. Therefore I take a
keen interest in all ISDN related threads on Asterisk lists.

Modifying the PRI code to accept BRITE signaling has been discussed in
this thread but unless I missed a message nobody has done so as of yet.
Mr. Brown was putting forth a hardware solution by Paradyne that I was
unaware of and unable to find detailed specifications regarding. I was
merely pointing out that the hardware he was describing might not be an
out of the box plug and play solution if its aggregate isn't a PRI. 

ISDN PRI channel banks never made great in roads in the US; most LEC's
and CLEC's utilized BRITE systems for the limited demand for ISDN that
peaked half a decade ago. The Brite channel banks are strictly used to
extend the range of ISDN BRI circuits in low density applications along
with analog circuits. This includes extending them from a capable
exchange to another non-capable exchange or to a neighborhood
distribution hub. Therefore the odds of any channel bank purchased on
Ebay supporting PRI/BRI are pretty slim. 

In the end user market, the Adtran Atlas series boxes are the only
widely available PRI/BRI device but they have a hefty price tag, $400
per BRI port or more, which limits their cost effectiveness. This is
especially true in light of Asterisk analog port options that are on the
order of $30-$75 per FXS port. Utilizing channel banks with the Brite
interface could drop the per BRI port cost below $100 as these are
readily available on Ebay and less expensive than the Atlas series
hardware to purchase new. Developing a multiport PCI card utilizing the
HFC chipset could bring the BRI port costs in line with analog
installations utilizing the TDM40B.

I heartily support any efforts to incorporate Brite communications into
Asterisk or develop a multiport HFC chipset interface card. I wish I had
enough knowledge of Linux and programming to attempt the BRITE driver
myself or the hardware background to develop the card but alas that
isn't the case. I will therefore have to sit on the sidelines and await
the efforts of other Asterisk developers.

Regards,
George Bean
Puwaba Technologies