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PRI ISDN, callback and MICA technology

  • From: Eugenio Pierno
  • Date: Tue Jun 06 05:32:16 2000

Hi folks,

is there anyone here who wants to share experience with Cisco's 3640 and
callback over a PRI ISDN?
We are having troubles and probably going to give up and switch to other 
solutions, but not before consulting with the people on this list (Cisco
TAC already consulted..)

We have a 3640 with 3 banks of digital MICA modems and want to terminate
both analog and ISDN calls over a PRI ISDN on the Cisco. The Cisco should
callback over the PRI to *both* analog and ISDN users. All of the 30
available B channels should be dedicated to this purpose.
That's all, is that possible?
We are using IOS 12.1.1(T), MICA Portware, E1/PRI ISDN ctrl,
client modems USRobotics, Multitech, Supra etc. 
So far callback works, with a TACACS+ based AAA scheme, but we have the
following problems:

- a high rate a unsuccessfull incoming calls (~50%) with the modems idle
and a busy signal or no answer at all (debug on Cisco shows a generic ISDN
disconnect error)  
- during the callback the modems do not handhshake properly, even
disabling V.90 and K56Flex (S29=1) so the Cisco drops the carrier after a
(long) timeout
- we need to reload the Cisco every second day in order to get a 
reasonable % of successfull incoming calls (and test, and test...)
"clear modem all" doesn't do any good. 
- the ISDN line is clean, "show cont", "show int ser 1/0:15" show no
errors at all. We use the "framing no-crc4" command on the controller, 
otherwise it goes down with "alarm detected", does this matter?
- Cisco TAC say our configuration is correct, why then it doesn't 
work? They are am I.

Anyone with similar experiences? 

BTW, we do have the "modem country mica netherlands" and "modem
autoconfigure type mica" in the config...

Thanks indeed in advance.

Eugenio Pierno
Amsterdam - The Netherlands