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Joined: Aug 2014
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Issue began on incoming calls at first, where after working fine for several days, all incoming calls (on channel one) would fail. Monitoring channel one, it shows as "idle", and the state never changed when a failed inbound call occurred. I set channel one to busy-out thinking it would roll to channel two, but would still attempt only on channel one and then fail. Returned channel one to service, and calls come through again. After approx 24 hours the same issue would re-occur, and busy-out/return on channel one would remedy again (temporarily).

I thought maybe simultaneous incoming and outgoing calls were colliding on channel one and locking it up, so I re-programmed the trunk group in reverse order from 15 to 1 (only 15 channels available on this PRI). All was well for a couple weeks, until calls started failing again, but now both inbound and outbound. When inbound fail, I busy-out/return channel one and they start flowing again. When outbound fail I busy-out/return channel fifteen and they start flowing again. As it was for inbound, the state of channel fifteen always shows "idle" during a failed outbound attempt. Obviously this is not an acceptable permanent solution.

Given the usage at this site, I highly doubt there are fifteen concurrent calls in the same direction, either in or out, that would cause an inbound/outbound simultaneous pair of calls to occur on one of the same failing channels, either one or fifteen.

Any suggestions?

Thanks.

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If you don't have a Tberd, or other channel monitor, then you have to it the old fashioned way. Replace the PRI module and check the status after 24 hours. You may also have a defective channel unit. Is the carrier using an Adtran? I have seen weird problems with a flaky smart jack.

It is nearly impossible for two calls to occupy one channel. The way the channels are designed, the "channel available" and "channel busy" bits change at near the speed of light, much faster than either the CO or the PBX can allow the calls to collide. The B channel monitors channel availability and a call can sit in the channel "queue" for what must seem like an eternity to an electron, for 10 ms before it actually changes bits in the channel for connection. That's roughly 100 channel available/unavailable checks before the channel comes up as in use.

Rcaman


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I do not have a Tberd, unfortunately.

The T1 card was previously used for a T1 (not PRI) less than a year ago. The PBX was switched to POTS lines, now to back to the T1 card, but with a PRI this time.

There is no Adtran in use.

I'm thinking it's a config issue on the PBX. The vendor reused the config from prior T1 circuit for the current PRI circuit, and I had issues getting that working from the beginning. Now this issue has come up. It was a COS setting that got the circuit working. Anything else in there that would be different between a T1 vs a PRI?

Thanks.

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Where do I start? You need to get some info from the carrier, first. We all assume it's ESF B8ZS, but just MAKE SURE! I actually had a Windstream PRI setup by Windstream as ANI. I don't know why, but it worked...sort of. Weird problems would crop up from time to time. The TBerd found it.

Next, check circuit descriptors or the PRI module's channels. Then check all the forms associated with T-1/PRI. There is one form there that MUST be changed from T-1 to PRI. You'll see it because it deals specifically with PRI. Then make sure your clock is set for the B/S/C of the PRI.

No one will give you specific programming information here as that is beyond the scope of this forum. If you need programming help, you may want to contact a Mitel dealer in your area.

Rcaman


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A well-respected NEC tech support guy, who shall remain nameless, noted that PRI protocols tend to be a bit "slutty" -- they just might sort-of work with the wrong settings.

As RCAman said, check B8ZCS/SF -/ESF versus AMI/D4, and make sure that you match the Telco.

Also, remember (in case it's not obvious) the BIG difference between T-1 and PRI, namely, the D-channel. I have had to rescue the D-Channel from IT Guys who wanted to carve out some IP Channels on the T-1.

Last but not least, make sure that you match the Telco on which PRI protocol you're using -- National, DMS, or NI-2.

Hope that helps.

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Hopefully you are not trying to do this with the old T1 card and are using a PRI card now unless it I a T1E1 module on a 200 ICP.

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LOL....I have never tried to do that. I don't see how it could work, at all, because the T-1 module treats the B channel like the other 23, so there would be no channel data for the other channels to parse the data properly. Now you make me want to try it just to see. https://sundance-communications.com/forum/images/icons/default_dark/smile.gif

Rcaman


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I don't think it should work at all either but I had to ask.


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