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Problem with PRI and Nortel Integration

We have a Nortel Option 81C connected to a 3825 MGCP gateway and we had a weird problem with it. The PRI looked fine from CallManager's perspective, but the PBX was showing that the first nine channels were in a Far End Make Busy state (FE MBSY) instead of being in IDLE state like CCM thought.

I did some checking around and found a weird "fix" for the problem that involved enabling and then disabled D-channel service messages on the PBX, but I'd like to find out more about this problem. I got the fix from a guy who has a LOT of experience with Nortel and with Cisco, and he said that 99 times out of 100, an FE MBSY problem like this is going to be because of the Cisco side, not the Nortel side.

I just did a bug search through CCM 4.1(3) and IOS 12.4(8) and I didn't see anything about D-channels being incorrectly reported as unavailable on PRI.

Have any of you ever heard of something like this?




Re: Problem with PRI and Nortel Integration


Our 81Cs are long gone, but the only ISDN switchtype that worked flawlessly for us was NI. We tried DMS100, and saw your problem. Nortel sees NI as a carrier side protocol and will not allow an inbound NI call to tandem through to another NI PRI. This forced us move all PSTN PRIs to CCM gateways early in out migration, but worked out well. I believe QSIG will also work, but it was a $20k upgrade for our PBXs, so was not an option.


Community Member

Re: Problem with PRI and Nortel Integration

I opened a TAC case about this and was told that the D-channel service and service acknowledge messages in LD96 should be turned on. We had them turned off. I was also told to uncheck "Inhibit restarts at PRI initialization".


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