Problems with inbound calls from SunCom

Posts: 51 · Full Forum Member Joined: Nov 02, 2008 Posts: 51

I have one frequent caller, on SunCom wireless who almost always has a problem. Either I can't hear them or the reverse, or both. This of course results in spouse screaming that "I hate that you made me get this goddamn phone!!!!"

Anyone have a suggestion? Anyone?

Posts: 355 · Posted: Mon Dec 15, 2008 8:39 am Post subject:

Did you ever think that it might be a SunCom problem, not Vonage. If that is the only caller with problems, it is most likely his problem not yours and changing to another provider would not make a difference.

Posts: 51 · Full Forum Member Joined: Nov 02, 2008 Posts: 51

Yes of course, but that's neither here nor there. Any suggestion to remediate?

Posts: 656 · Posted: Mon Dec 15, 2008 10:20 am Post subject:

All calls for you will terminate through the same point from non Vonage lines to the Vonage network. Depending upon which market your phone number comes from will determine which Vonage partner carrier's switch your number is built into. When a call hits their switch, they send the call to a Vonage inbound GW in a specific location. So regardless of where the caller is or who their phone company is, all Inbound calls to your phone number enter Vonage's network at the same point.

Example:

Your number is from Boston, MA. Vonage's partner carrier for that market is Focal. The trunk groups for this market from Focal to Vonage terminate in the Vonage NYC datacenter. If you receive a call from your next door neighbor or from a caller located in China, both calls will hit the Focal switch for Boston and be transported to Vonage's trunk group in NYC. So there is no difference of who the caller is. All inbound calls to your number route the same.

Now, what might be different is the transport path between the caller's company SunCom and Vonage's carrier Focal. There are many different underlying providers that route calls in between 2 end points. Calls do not route from Point A to Point B for the most part unless it is an in network call. So the issue could be a fiber run or a specific T-1 trunk group that sits somewhere in between SunCom, the carrier they are sending the calls to in order to reach Focal.

The best course of action is to have the caller open a ticket with SunCom and provide all the details of the caller's experience.(1 way audio, dead air, echo). Once they have a ticket #, contact Vonage and ask to be transferred to Advanced Operations. Tell the person you speak in Advanced Operations exactly what the problem is and address the points I speak about in this post. Also provide them with the SunCom ticket number. They will open up and ticket with your inbound provider and reference the SunCom ticket #. If they fail to properly handle this issue, get their name and PM it to me.

There is no guarantee that Vonage's provider will be able to resolve this for you since this is NOT an issue with their trunks. It is most likely an issue with the trunks of an underlying carrier in between as mentioned before. This is rare but I have seen it a few times before where a specific trunk group is not configured properly so the D channel will set up the call and B channels will show activity yet no audio is being passed.

Also be aware that in the case of both SunCom and Vonage's inbound carrier, test calls from the caller to you will be required and may require many as the calls will need to be trapped to see where they go.

Posts: 51 · Full Forum Member Joined: Nov 02, 2008 Posts: 51

Excellent, thank you

Posts: 831 · Vonage Forum Evangelist Joined: Jun 08, 2007 Posts: 831

VonTechMgr wrote:

Now, what might be different is the transport path between the caller's company SunCom and Vonage's carrier Focal. There are many different underlying providers that route calls in between 2 end points. Calls do not route from Point A to Point B for the most part unless it is an in network call.

Great explanation, this shoul be a sticky on this forum on how calls are routed!

BTW, one question about routing calls to endpoints. When a SunCom customer calls the Boston number (which has been ported from The local telco), does it go through the Telco in Boston who owns the number and via a trunk go to Focal, or is there a lookup elswhere that tells SunCom to go directly to Focal? i.e. how does SunCom know to go to Focal?

Posts: 656 · Posted: Mon Dec 15, 2008 12:58 pm Post subject:

Well the use of Focal and Boston was only for an example. I don't know what market or carrier Pyramid3's number belongs to since I don't know his number.

But to answer your question, SunCom or any other carrier has to do an LRN lookup prior to routing a call. The LRN(Location Routing Number) has been used every since Local Number Portability was introduced. While the incumbent carrier may own the NPA-NXX 301-755 and block number 4,(example number 301-755-4321) other carriers knew where to route these calls since only 1 carrier switch could possibly own this number.

Now after LNP has occured through the country, an LRN was needed in order to locate a specific number. So when a number ports, the incumbent carrier releases the number from the switch, new carrier builds it into their switch, performs a broadcast, and NPAC database is updated. The LRN acts in the same way a routing number on a checking account would. You phone number is the checking account number and the LRN is the routing number to your bank.

When the originating provider goes to route the call, the must have the correct LRN and if they don't, they terminate the call to the old switch where number no longer exists. This is where people complain that they can't get calls from certain people and caller gets a Disconnected or not in service message. Again, not a fault of Vonage or their carrier.

In order to see where the actual call goes once it leaves SunCom would require an SS7 trap performed by SunCom to see whose Destination Point Code it hits. Focal could also do the same on their side to see whose incoming trunk group the call is coming to them on. The call from SunCom would not route to the Telco that the number ported away from. If it did, it would fail to complete as it would be terminating to their switch that no longer houses the number.

Is the information you were looking for?

Posts: 831 · Vonage Forum Evangelist Joined: Jun 08, 2007 Posts: 831

That was exactly the information I was looking for. THANKS!

I always wrongly assumed that the local telco who owns the number merely relayed the call to the Vonage local provider. The method you outlined seems much more efficient, much like a URL to an IP lookup via nameservers.