asterisk users - Apr 2003 - ISDN phones & Asterisk, ASDI and then some

Hello all,

New to the list, Asterisk and this wonderful world of convergence. From
reading the docs, list and websites I hopefully correctly understand
that I can use a plain cheap isdn4linux supported ISDN (passive) TA to
hook up the PC to the ISDN line from the telco (FXO card?). Next in the
PC I also need a FXS card like a Digium TDM10B or PhoneJack so I can
hook up an analog phone to it.

In sort of graphics:

analog phone === FXS card - PC - FXO card === Telco/PSTN
                 PhoneJack       ISDN TA      ISDN
                 Digium TDM10B

Questions:
1) Is my description above right?

2) Is there a FXS card to which I can connect an ISDN phone?
   I have read some messages saying it can not be done with current *
   I read that a Teles ISDN TA can be configured as a TE (terminal
   endpoint) *or* NT (network termination). It's the ability to be
   configured as a NT which seems to be the solution. If the FXS TA were
   configured as an NT wouldn't the ISDN phone think it was hooked up to
   the PSTN. Now only * needs to do some magic :) Makes sense?

3) is it possible that an existing pbx infrastructure is upgraded to an
   * solution where the existing phones can talk to * just fine?
   In other words: is there a general compatibility between phones from
   various brands and PBX's from other brands? It would financially be
   less attractive if a customer would have to buy a whole new set of
   phones...

4) what is an ADSI phone? I read on the list that they are cheap ($50)
   so I may want to invest in a couple in case * can't talk to my ISDN
   phones. Any vendors websites were I can read about these ADSI phones?

5) Integrating xDSL in an * box seems like an idea re VoIP. Anyone
   have some suggestions what brand PCI ADSL cards work with Linux and
   play nice with the Telco's DSLAM equipment (preferably in .nl)?

6) any DECT (for digital wireless phones) PCI cards and DECT Cells out
   there with Linux support? Would be cool to be able to offer service
   to wireless digital phones also

7) Finally, are there any business cases with some nice financial
   numbers that compare e.g. a basic 4/16 * based building block to
   commercial offerings in terms of pricing, functionality, scalability
   etc.?

Thanks for your time and advice!

Cheers,
Patrick

Patrick,

--On Tuesday, April 22, 2003 12:58 am +0200 Patrick 
<idefix@puzzled.xs4all.nl> wrote:
> I hopefully correctly understand
> that I can use a plain cheap isdn4linux supported ISDN (passive) TA to
> hook up the PC to the ISDN line from the telco (FXO card?).
Yes you can.  I have had asterisk running with an Elsa card I picked up for 
?5.  However, most cheap cards are "passive" (ie they don't have
much
processing on board) and rely on the isdn4linux software.  Isdn4linux 
presents a modem like interface to asterisk.  The limitations I have found 
(in the UK) are principally with echo on the local side although some delay 
is also introduced (not serious).

In contrast, active cards (eg some of those from AVM) have on-board 
processing and support the CAPI interface.  Some also support echo 
cancellation.  You operate these cards with the asterisk chan_capi driver. 
People seem generally to be happy with that although I have no experience 
with it.
> Next in the
> PC I also need a FXS card like a Digium TDM10B or PhoneJack so I can
> hook up an analog phone to it.
>
> In sort of graphics:
>
> analog phone === FXS card - PC - FXO card === Telco/PSTN
>                  PhoneJack       ISDN TA      ISDN
>                  Digium TDM10B
>
> Questions:
> 1) Is my description above right?
>
Not exactly.  You could connect a phone to the PC through an USB adapter, 
which would go:

  analogue phone === USB interface (S100U) - PC - ISDN card === Telco/PSTN
                                                                ISDN

If you have an ordinary analogue PSTN line, buying the Digium Devkit Lite 
would be a good starting point.  You could use an FXS card for a local 
analogue phone as you suggest but there would be no need for an FXO card if 
you have an ISDN card in the PC.

If you have an ISDN TA then you could install an X100P in the PC and 
connect it to the TA (I have done this).  However, be warned that the 
Digium hardware assumes US signalling voltage patterns on the line.  These 
may not be provided by your TA (I had to modify the driver code to get the 
X100P to work with my ISDN TA - it now works fine).
> 3) is it possible that an existing pbx infrastructure is upgraded to an
>    * solution where the existing phones can talk to * just fine?
>    In other words: is there a general compatibility between phones from
>    various brands and PBX's from other brands? It would financially be
>    less attractive if a customer would have to buy a whole new set of
>    phones...
Probably not - commercial IP PBX vendors have a problem with this in the 
market.  Commercial products such as 3Com's NBX can be equipped with 
adapters (from Citel) so that they work with Nortel digital PBX phones. 
There are other options but in general PBX vendors like people to keep 
their phones and PBX ;-)

  Iain