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New Member

ISDN in Japan

Anybody here who's from Japan? Or might be familiar with the ISDN configurations in Japan?

I'm trying to setup a H.323 Gateway on a 2600 with NM-HDV-1T1-24.

When I do a show controller, it says:

T1 1/0 is down.

Applique type is Channelized T1

Cablelength is long gain36 0db

Transmitter is sending remote alarm.

Receiver has loss of signal.

I'm thinking that it might be a cable problem. But NTT says their equipment is ok.

Router is connected to ISDN 1500 equipment with a RJ-48 cross-over.

The ISDN is for voice only.

What other things do I have to check to make sure it's working?

The technical guys who installed the ISDN line, didn't have much information about the connection.

Cisco Employee

Re: ISDN in Japan

Put the T1 in loopback (loop local line) or use a T1 loopback plug. IF it does not come up like this, there is probably a HW issue with the card. If it does come up and run clean in loop mode, the problem is probably the cable or other end.

Re: ISDN in Japan

I thought japan had their own type of T1 technology which is usually referred to as J1. Even Cisco has a Nm-HDV-1J1-30E.

Are they able to loop your circuit and run clean ?

New Member

Re: ISDN in Japan


I am heading to Tokyo to setup a T1 to Chicago. What information will I need while in Tokyo and/or Chicago? We will be using Cisco 2620's. How is it working with the local telco's? What problems did you run into and what should I expect? Any info would be greatly appreciated.

New Member

Re: ISDN in Japan

The T1 is working already for a few months now.

Its just that I wasn't able to update this thread.

Here is what happened.

Because of communication problem, there where things that wasn't really so clear. I don't speak japanese, and the NTT technical doesn't speak english either. So we have some sort of translator in between. I haven't been to the Japan office, all configurations/testing/debugs are being done from my desk. Translator was one of the staff on the Japan office. And also speaks little english. All work was done with the help of the staff in japan. They took pictures of the LED for the alarms, translate the recorded message when we tried calling the ISDN line, replacement of the cable during the loopbacktest.

NTT said that their ISDN PRI works with PBX only. It doesn't work with Cisco router/gateway. And they said that if we connect the ISDN line to a cisco equipment, they won't support it.

They said, it should be connected to a PBX first then the Cisco equipment is connected to the PBX.

We explained to them that we won't be using a PBX cause the router is a Gateway to a Cisco Callmanager. And putting a PBX in between makes no sense cause we'll still have a T1 connection from PBX to Cisco router. It will just be a waste of resources (buying another PBX?). They then point-out that their other T1 installed in that office was working fine for a few years now and its connected to a PBX (already existing on that site). So they are pretty sure that it works with PBX only.

After having the problem above, we gave them a call to check their equipment and the link. After a few days and a few visit after, they said that their equipment is working properly and they did a loopback test.

So I did a loopback test as recommended by crieman, there was no issue on the hardware and configuration. Everything was configured properly and hardware are ok. We even had TAC connect to the equipment to double check. TAC said everything is fine, the line had the problem.

After a month of having the problem and we're going nowhere, we decided to get a PBX to connect to the T1 line. We talked to the supplier who configured the existing PBX and see if they can rent us a PBX with T1 connection for a few days.

PBX supplier came in, attached the PBX to the T1. They try to configure it but they have problems too. They called up NTT. NTT arrived and check for problems. A few hours later, restarted all their active equipment on the site. T1 was up, we transfered it directly to the Router without configuring it in the PBX.

Router detected it us up, we tested incoming and outgoing calls thru the callmanager. Everything works.

NTT didn't say a word about it when they saw that it works with the cisco router.

Other than the physical and NTT problem, its pretty straight forward.

I did hear about the specific module for Japan, but when I talked to TAC, they said my existing equipment should work fine.

Hope any of those info helps.

New Member

Re: ISDN in Japan

That doesn't make sense that a ISDN PRI would only work with a PBX. I'm actually in Tokyo right now trying to figure out providers to use and what to order. We are using Sprint as our T1 carrier to the states (point to point to chicago). What carrier are you using and how long did it take to get the circuit installed?

How difficult was it to order a ISDN PRI from NTT and how long did it take to get the circuit installed? Would you recommend just leasing a PBX? Can you list the Cisco Part #'s and cable interfaces you are using for the router/gateway? How easy is it to lease a PBX with a block of 50 DID numbers? Who do you lease the PBX from, NTT?

Do you have any good contacts at NTT who are aware of your issue? I would really appreciate your time, as I will only be here for a couple days to get all of this situated. Any other helpful tips would be greatly appreciated. If you want to contact me directly....

New Member

Re: ISDN in Japan

TAC is right!

You should be able to connect NTT T1 line straight to your cisco equipment. Make sure you configuration is ok and you should be fine.

New Member

Re: ISDN in Japan

What are the hardware specs for your WIC card? I need to order an interface for a 2621 here in Japan to the US and I'm wandering what your using.

What is the CSU/DSU interface and what is the type of cable you are using to connect from CSU/DSU to the router?

Also, what is your configuration you used for T1 (line coding, framing, etc)

New Member

Re: ISDN in Japan

T1 Module used is NM-HDV-1T1-24. But I would recommend VWIC-1MFT-1T1 with AIM-Voice-30. Much cheaper solution and it doesn't use the NM slot.

Unless you have another AIM already on your 2621 router, then you'll have to use the NM module.

CSU/DSU cable used is an RJ-45 to RJ48 straight cable

Configuration for T1: linecoding b8zs, frmaing esf, switch-type primary-ntt.

New Member

Re: ISDN in Japan

We will be using the following router and card




Is the CSU/DSU cable a RJ45-RJ48 straight or reverse (I noticed in your previous post you mentioned a crossover)? RJ-45 plugs into VWIC and RJ-48 in other end?

Is this the same cable you use for a Data T1 in the integrated WIC port? Any issues setting up your data T1?


New Member

Re: ISDN in Japan

My apologies for the confusion. The cable we are currently using is a straight cable. We ordered it from a local cable company in Japan.

The link is:

We ordered the first one. You might want to try to use babel website if in-case you want it on english translation.

The documents said that the VWIC-1MFT-T1 should be an RJ-48, but our japan office says that its an RJ45 on their end. The CSU/DSU has an RJ48 connector. So to be safe, we ordered the RJ45-RJ48 cable. RJ45 cable should fit on the RJ48 slot but not the other way.

New Member

Re: ISDN in Japan

Did you configure the Dial Plan (calling search space) for the Call Manager in Tokyo? If so, do you have any recommendations or examples. Has anyone used the download from Cisco for the Japan International Dial Plan? If so, was it helpful and how did it work?


New Member

Re: ISDN in Japan

Hi there,

I had it working on Catalyst 6509. T1 was setup as a FXS gateway (not H.323). Hope this helps if not I think i could find some samples files.

Bobby Marinkovic

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