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ISDN switchtype

Hi all,

I am new to the CCNA voice world. First of all, I come across to the ISDN switch type in some website, but I still cannot get the clear picture of this concept. May I know where I can get the ISDN switchtype that to be used in our voice network environment and why do we need to use this switchtype?

Any help and advice is highly appreciated.



Re: ISDN switchtype


In order for any ISDN lines to establish Layer-1 connectivity the switch-type has to be defined correctly.

The switch-type is very much country dependant so it’s also important to memorize the switch-type that applies to where you do most of your installations.

If Layer-1 is showing ‘Deactivated’ when using the show isdn status command, only 3 things can be the source of the problem.

1/ isdn switch-type has not been set, or has not been set correctly (The most common problem)

2/ There is a problem with the PSTN (call your telephony service provider)

3/ Cable problems

4/ Physical port failure on the Router.

In order to configure the switch-type you can enter the command

Isdn switch-type {switch-type}

This can be done either in global configuration mode, or on the interface depending on the router and IOS version.



Re: ISDN switchtype


Here is a document, which explains what type of isdn switch type you have to use depending upon the PRI / BRI Interface you have.

ISDN switch type of basic-ni is used for BRI interface . For PRI interface (T1/E1 controller), you have to configure ISDN switch type primary-net5.

Pl rate if the info is useful. Thanks.

Cisco Employee

Re: ISDN switchtype


The only way to know for sure what switch type to configure on your side is to ask the other side what they are configured for.  Most providers use the terminology 'ISDN protocol' or 'ISDN protocol variant'.

Note that you can run a 'national/NI' protocol on top of a physical 4ess, 5ess or DMS100 switch so you need to be specific in the protocol variant running, and not what physical type of switch it is terminating on.  In my experience, national is the most common, followed by DMS100.  ATT circuits are often 4ess or 5ess.

I always ask them what they have provisioned.  I never phrase it as 'are you configured for XXXX' because often they will just respond with 'yes' instead of actually looking it up.  Phrasing the question in the former format forces them to actually look at the configuration.

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