atcomsystems.ca/forum Forums TDM Business Telephone Systems Toshiba Telephones & Systems CIX Outbound Trunk Selection

I have a system running Version AR4.20 MP026.00 that has been experiencing a strange trunk selection problem on outbound calls. I am wondering if anyone has seen this before and knows a solution.

There are 2 PRIs that are 2 way, each with their own D channel, and regardless of inbound or outbound calls they are configured to route in reverse order starting at channel 23 and going up (22, 21, 20 etc). When that circuit is all busy it should hunt to channel 46 and route backwards through the second PRI.

That all seems to work fine with one exception...randomly channel 46 will get tagged for an outbound call bypassing whatever channels are open on the first PRI. It is always on Outbound calls. I have watched it happen and cannot find any patterns and even have duplicated the problem myself by sheer luck. We have never filled that first PRI to my knowledge so calls should, in theory, never have hit that second PRI.

It is not based upon a particular trunk because it does not always happen when X number of trunks are busy or anything like that. We can have 1 active call or 10. It does not happen to just certain extension, it seems to happen to anyone and it only occurs 4-5 times a day. I cannot find any patterns so far.

Anyone ever seen something like this and have a suggestion for me to check? Thanks a bunch.

If you're using LCR to route the outgoing calls, the only logical reason for the call to get routed to the 2nd PRI (channel 46) is that the first PRI is down (for a split second).

Try to swap the lines for testing and see if it happens.

Thanks for the reply, would that not affect inbound calls too? Also, in that scenario do you think the active calls would drop?

That sounds like a great test, we will see if that fixes the issue.

I think it should affect inbound calls too, but in your case, it doesn't?

Drop? Sorry, I'm not sure.

We have a few PRIs in our office, and it only spills over to the 2nd PRI once the first one is full (30 channels here).

You can try to change the B-channel selection method in Prg 302 and test.

You also can monitor each PRI usage via traffic measurement. Then you drill down to the hour that this happens, the no. of times that it spills over and also incoming call traffic.

...and btw, how is this a problem? =)

It really isn't so much of a Problem, but more of a mystery. I have never seen any other type of equipment do this so I was trying to figure out of this is a common occurence on a Toshiba system.