[cisco-nas] X.75 and modem dial-in, autocommand to TCP

[marc at belbone.net]

Gert,

I don't think Cisco ISDN equipment supports X.75.

Many years back we had US Robotics Total Control with dual PRA per 
card, these can do it.
USR was sold to 3COM, no idea this is still supported officially.

I think the later versions of firmware of the 3COM support syncPPP 
and this works perfectly on a Cisco access servers or routers with 
ISDN interface (PRI or BRI)
In this case you don't need 'modems' on the Cisco router

Maybe this helps too.
ftp://ftp.usrsupport.ru/datasheets/0698-ds.pdf

Marc Neuckens
Belgacom


At 09:45 11/03/2009, you wrote:
>Hi,
>
>a customer of ours currently has a dedicated PABX which is feeding an
>ISDN PRI into a bank of about 20 "ISDN modems" (USR Courier I-Modem,
>which do X.75 and "V.34 stuff" modem calls).  Modems are connected
>to serial terminal servers, which in turn connect to an AIX unix system.
>
>Customer is unhappy, because these take up lots of space, the PABX is
>expensive, modems crash and need a reset, USR Courier I-Modems are not
>sold "new" anymore, and so on.
>
>So the idea was to build something with a router - PRI channel into
>router, "transparent TCP stream" out of the router to the AIX system,
>to be handled by a something like telnetd.  We can handle everything on
>the AIX side, the questions are on the router side :-)
>
>  - as far as I understand AS5xxx boxes, this should be doable with
>    an AS5350 or the like
>
>  - what do I need to terminate X.75 calls?  Do I need modem DSPs, or
>    will the X.75 be handled by the "digital side"?
>
>  - I assume that X.75 calls will end up on a "line async ...", so I can
>    put an "autocommand" there, to immediately connect from the router
>    to the host at CONNECT time (*no* prompting or any sort of messages
>    from the router is permitted).
>    Will that work?  It MUST be a) completely 8-bit transparent (Zmodem
>    transfers over X.75) and b) completely silent (end user call-up scripts
>    get upset if 'yet-unseen' messages show up).
>
>  - is there Cisco gear that can handle X.75 on BRI lines (so we could
>    develop and test this on an ISDN S0 port, without disconnecting the
>    whole PABX)?
>
>  - some of the clients have 'issues' with X75 window and block sizes - can
>    this be tuned on the Cisco side, as in "we need to have the X75 block
>    size set to 4096 byte on reception, 8192 on transmission"?
>
>
>If Cisco cannot do this - any other gear that's still sold and supported
>(important!) that one could use to terminate X.75 and modem calls?