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New Member

ISDN2 Back to Back conf (VIC2-BRI to Video Conf Unit) is this possible?

I have a VIC2-2BRI-NT/TE which I need to connect to a Video Conferencing unit. I have configured the following but I'm getting no layer-1.

interface BRI0/2/0

description *** VC

no ip address

isdn switch-type basic-net3

isdn protocol-emulate network

isdn static-tei 0

I have tried both straight through and ISDN crossover cables as below.

3 -> 4

4 -> 3

5 -> 6

6 -> 5

Can anyone offer an advice on this?



Hall of Fame Super Gold

Re: ISDN2 Back to Back conf (VIC2-BRI to Video Conf Unit) is thi

You need a crossed cable and also "isdn layer1-emulate network".

Hope this helps,m please rate post if it does!

New Member

Re: ISDN2 Back to Back conf (VIC2-BRI to Video Conf Unit) is thi

I already had that configured and it hasn't helped (although it wasn't in the config I had shown). Thanks for your input anyway.

I actually found this Cisco Doc

But its still not working so maybe I have a cabling issue or theres something up with the VC unit. At least I know now that the config is correct.

Cisco Employee

Re: ISDN2 Back to Back conf (VIC2-BRI to Video Conf Unit) is thi

The following URL might give you some more ideas on how to do TDM switching through the BRI/PRI voice ports -

If you are outside of North America, remember to set the companing to a-law on the voice port - once the call connects the DSP will be dropped and a pure TDM connection made as long as the E1 and BRI companding are the same.

Some external BRI devices don't like to negotiate a TEI, so you can set a static TEI of 0 using the D channel command 'isdn static-tei 0' and doing a shut/no shut on the interface.

If this still does not help, run a debug ISDN Q921 and log the results after plugging in the external unit and performing the shut/no shut on the D channel.