Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

ISDN in Mexico

Does anyone have experience of ISDN in Mexico City. We have a customer we are trying to provide ISDN backup there for.

Telmex supply the BRI ISDN line which terminates on an Intracom Netmod NT1 modem and provides an S/T interface. The ISDN service is Euro ISDN (basic-net3).

The problem is that Layer 1/2 are down, and Telmex advise that the router needs to provide an Active ISDN interface, but I have been able to find a way to do that.

Telmex, say they have sometimes provded an active D channel, but it is not possible in this area.

The ISDN line will accept incoming ISDN calls from USA, but I can not generate a call from Mexico City.

I have tried the "isdn tei-negotiate first-call" but this doesn't help.

Has anyone come across a similar situation or any suggestions I can try.

The router is a 2600 with ISDN WIC S/T card and 12.2(5) IOS.


Re: ISDN in Mexico

If you are able to recieve calls from USA, It means layer 1/2 is coming up while recieving the call.

Try this command also in the URL

isdn tei-negotiation (interface) in the interface mode

And check for any vital commands you are missing in the configuration

Cisco Employee

Re: ISDN in Mexico

First of all, you need to make sure that LAYER 1 should be up for bri line. If not so, you need to talk to telmax for that. Also make sure that the NT1 device is configured correctly.

Here are some urls to troubleshoot in that area

Layer 1 troubleshooting

Layer 2

Troubleshooting ISDN BRI Layer 3

Performing Loopback Calls to Test BRI Circuits

CreatePlease to create content