[VoiceOps] Tandem Dropping Calls

Tue Oct 4 14:46:52 EDT 2022

To close the loop... 

This morning Frontier reported an errant CIC code being sent with the call, but didn't know if that was the cause or not. My own troubleshooting proved that out. I ended up checking Metaswitch and found a variety of other customers with bad CIC codes entered. No idea why they haven't had issued, but I'll have our people fix all of them. 

Once I fixed the CIC code for the problem customer, I found that one of the three numbers was rejected for no destination, verifying to me that NPANXX isn't on that tandem and removing it from that NV table. 

Frontier called 15 seconds after I implemented the last fix. I explained everything to the guy that called and he said, "That's not the strangest thing we've had lately, but it sure is up there." 

I feel vindicated when the other party is as confused as I am, but then embarrassed when it was a silly garbage in\garbage out problem. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest Internet Exchange 
http://www.midwest-ix.com 

----- Original Message -----

From: "Mike Hammett via VoiceOps" <voiceops at voiceops.org> 
To: "Mark Timm" <Mark.Timm at aureon.com> 
Cc: "VoiceOps" <voiceops at voiceops.org> 
Sent: Monday, October 3, 2022 3:03:29 PM 
Subject: Re: [VoiceOps] Tandem Dropping Calls 

*nods* Frontier doesn't make it easy to send them logging information from my side, short of source, destination, time. 

We do our own LNP and route accordingly. It is pretty simple, though. All of the rate centers off of this tandem have Frontier as an ILEC, so I just pulled all of the NPA-NXXes in those towns and throw them at the tandem. Some of them we do have (I forget the telco speak for this) direct peering with a few of the Frontier switches. 

I have had some cases where a non-ILEC operator was on a different tandem that I would have expected, so I had to carve those out, but the above method has largely held up. 

The first ticket I threw at them, they couldn't even find two out of the three calls, and they just happened within 2 hours of ticket submission. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest Internet Exchange 
http://www.midwest-ix.com 

----- Original Message -----

From: "Mark Timm" <Mark.Timm at aureon.com> 
To: "Mike Hammett" <voiceops at ics-il.net>, "Nick Olsen" <Nick at 141networks.com> 
Cc: "VoiceOps" <voiceops at voiceops.org> 
Sent: Monday, October 3, 2022 2:39:18 PM 
Subject: RE: Tandem Dropping Calls 

If the LERG/OCN doesn’t designate a local tandem there is no local tandem and the call must be sent to the Access tandem or to carrier. If you are performing a LNP query and the LRN does not subtend Frontier they will not route the call. Generally if you don’t perform a LNP query and the pre-LNP NPA-NXX belongs to in this case, Frontier, Frontier will perform the LNP query, route the call and assess LNP, switching and transport charges to the originating LEC/you if the number is ported. 

Sending a log or call record with OPC / DPC and time stamp along with the ticket helps eliminate confusion if you are able to do that. 

In my experience ISUP 31 does indicate a routing/translation issue. 

Aureon.com		Mark Timm  
Switch Engineer 
	Aureon 
7760 Office Plaza Drive South 

West Des Moines 
	, 	IA 

	50266 

	Mark.Timm at aureon.com 
	515‑830‑0478 

	www.Aureon.com 
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From: VoiceOps <voiceops-bounces at voiceops.org> On Behalf Of Mike Hammett via VoiceOps 
Sent: Monday, October 3, 2022 10:34 AM 
To: Nick Olsen <Nick at 141networks.com> 
Cc: VoiceOps <voiceops at voiceops.org> 
Subject: Re: [VoiceOps] Tandem Dropping Calls 

[External Email] This message was sent from outside the company with a URL. Please do not click links unless you recognize the source of this email and know the content is safe. 

Calls through Bandwidth were successfuls, the last carriers (Frontier and VZW) don't have anything going on with my customer's TN. 

*sigh* Back to Frontier. I called Friday to escalate, but now the ticket in VFO is closed, so I'm sure that'll be wonderful to get them to act on now. 

It's the same tandem town\CO, but aren't LD tandems and local tandems different, or is that separation history and they just all get dropped on the same box now? 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest Internet Exchange 
http://www.midwest-ix.com 

----- Original Message -----

From: "Nick Olsen" < Nick at 141networks.com > 
To: "VoiceOps" < voiceops at voiceops.org >, "Mike Hammett" < voiceops at ics-il.net > 
Sent: Friday, September 30, 2022 3:30:48 PM 
Subject: Re: Tandem Dropping Calls 

Honestly the reply you got was more then I would've expected from any ILEC. This lack of care is par for the course for them. 

The way I read their reply however is "Trouble isn't in my department, go open a ticket elsewhere". And might be indicating that the reject is coming from somewhere further downstream. Such as they attempted to alert the line but it was busy. And they passed that back to you as a CC31 because... reasons. But this is a routing/translations guy, not an access guy. So he doesn't know. 

The ILEC's are so compartmentalized that the person that handled this ticket doesn't even know where you'd go from there other than it's not his/her problem. 

If I were you, I'd try sending the call to IQ or some other LD carrier and see if you get the same results. Atleast with the Frontier called TN's (2 of the 3), you know they're terminating back to that same tandem regardless of if it's from you or IQ, or whoever. Try the same call with different ANI's, Different results? Maybe the end user is subscribed to some service that is blocking the call..etc. 

Best of luck! 

From: VoiceOps < voiceops-bounces at voiceops.org > on behalf of Mike Hammett via VoiceOps < voiceops at voiceops.org > 
Sent: Friday, September 30, 2022 2:35 PM 
To: VoiceOps < voiceops at voiceops.org > 
Subject: [VoiceOps] Tandem Dropping Calls 

We have a new customer that has an increasing number of TNs they can't call. I've traced them all down to going through our local Frontier tandem. Calls from other phone numbers on our network are fine. Two of the numbers are with Frontier, just another ratecenter off of that tandem. The third we know of goes to VZW. 

I submit a ticket to Frontier with source number, destination number, and call date\time for the last set of problem calls, all within the previous 24 hours, out of our Metaswitch SAS. 

Frontier replies: 

Per Software Engineering/DBA: Did not find mention call in IRIS (SS7), did find at that time a call to 815-824-XXXX, not 815-824-YYYY. SS7 show that call at 14:51 came in on DNC tgn 1011, GN089085, OPC=005-092-136 and terminate to DeKalb switch. Verified 

incoming call in switch, switch not blocking terminating to line. **31 - Normal. Unspecified. This cause is used to report a normal event only when no other cause in the normal class applies**. Found no trouble in switch translations/routing. 

Status: 
Cleared Awaiting Cust Verification 

So we have a very different definition of "cleared". I call a problem cleared when it's resolved, not when the reason can't be found. 

So Frontier: 

1. Can't find one of the three calls I sent them. 

2. Doesn't chase the problem to the end of the line. 

3. Clarifies that the ISUP error I'm getting means they don't have a reason for it to be closed, so probably not a normal circumstance. 

4. Doesn't investigate why there's an unclassified release. 

How can I incentivize Frontier to actually figure this out? 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest Internet Exchange 
http://www.midwest-ix.com 

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