[cisco-voip] Carrier routing issue?

[Wes Sisk]

"occur as things are starting to get busy on the trunks"

This raises concern about glare conditions.  Not sure if your CO will 
continue hunting when a glare condition occurs.  This gets into very 
specific implementation details of the ISDN stack in both the CO and CPE 
equipment.  I've also seen ISDN protocol mismatches exacerbate this. At 
the simplest, verify b-channels remain in service. After that we need to 
carefully review d-channel signaling.

To look for further information I would start with review of CDR's on 
CM.  If inbound call fails for any abnormal reason it should be logged 
in CDR.

After that it may be useful to review CDR's from the IOS gateway itself. 
These come out in a slightly different format. "Show call history voice" 
may also be useful.

If all of those fail then setup CM trace archive and archive CM SDI and 
SDL traces through your busy hours.  It is possible to parse those and 
identify all calls.

Of couse, if the call is being dropped in the CO before any signaling to 
the CPE then we will not see any mention in our gear.

/Wes

On Thursday, August 05, 2010 9:14:26 AM, Dave Wolgast 
<dwolgas1 at rochester.rr.com> wrote:
> I am pretty confident that this does not have to do with CallManager 
> (6.1.4, MGCP PRI GWs with lots o' DIDs), but I am wondering if someone 
> might help me put together a method for approaching the issue...
>
> Sporadically, for what seems like about a minute at a time, some 
> callers to our DIDs (mostly cellular callers) report getting a network 
> message that the call cannot be completed, or for Verizon Wireless 
> callers, "the Verizon Wireless customer you called is not available at 
> this time."  My personal experience is that I retry 2-4 times, and end 
> up getting through.  It doesn't happen often, but does seem to occur 
> as things are starting to get busy on the trunks.  That said, I never 
> see blocking on the trunks when I monitor using RTMT, even though 
> utilization is fairly high.
>
> The DIDs are on a trunk group of 5 Verizon PRIs, and in 2008, were 
> ported by Verizon to a different CO when headquarters moved a few 
> miles down the road.
>
> Any ideas for things I should look at/for?  Should I be calling 
> Verizon, or any of the cell carriers on which the issue was reported?
>
> Thanks for any suggestions you might offer!
>
> -- 
> Dave Wolgast
> Livonia, NY
> ------------------------------------------------------------------------
>
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