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jimk
Premium
join:2006-04-15
Raleigh, NC
Reviews:
·Time Warner Cable
·voip.ms
reply to josephf

Re: Do All Calls to DID Go Through Original CLEC After Ported?

No, it doesn't go through the original CLEC equipment. When a number is ported, it is assigned a LRN. The LRN looks like a telephone number but works differently. It allows a call to be routed directly to a different provider's switch.

Look at this article and scroll to the bottom (section titled Call Flow to a Ported Telephone Number): »www.npac.com/number-portability/···np-works


josephf

join:2009-04-26

1 recommendation

It is interesting that both toro and jimk reference the same webpage (at npac.com) yet arrive at opposite conclusions to my original question.


azmike

join:2012-07-19
Phoenix, AZ

1 recommendation

Click for full size
And they are both right!

The confusion may be related to what is really meant by a "call". A call is NOT a singular, atomic "thing". A call is actually a "process" that in simple terms involves 3 "states" - setup, conversation, and teardown or release.

Have a look at this diagram (taken without permission from »www.cs.utexas.edu/users/vin/Clas···/ss7.pdf). All of the "crap" being sent on the Signaling Links is simply to make a Voice Trunk available between "A" and "B" and then teardown that trunk when someone hangs up.

So assume you ported a number from switch A to switch C (you technically don't port a number from a switch, but that's good enough for this simple example). Early in the setup phase Switch B would say "Nope I no longer have the number you dialed but it can be found at switch C". All the signalling "stuff" would then move between switch A and switch C with the goal of providing a voice Trunk between switch A and switch C. Switch B (your original CLEC) is now out of the picture.

So yes, some signalling still "goes through" your original CLEC but the voice trunk or conversation part of it does not.

josephf

join:2009-04-26
Reviews:
·VoicePulse

If understanding you correctly, the original LEC from whom the number was ported-out from can interfere and stop (whether due to equipment disaster or sabotage) all callers from reaching the destination DID. This is true even though the original LEC has no customer or business relationship with either the end telephone subscriber or his current LEC.



Trev
IP Telephony Addict
Premium
join:2009-06-29
Victoria, BC
kudos:5

1 recommendation

reply to jimk

said by jimk:

No, it doesn't go through the original CLEC equipment. When a number is ported, it is assigned a LRN. The LRN looks like a telephone number but works differently. It allows a call to be routed directly to a different provider's switch.

This has been my understanding as well, but on that token I do not work on this kind of equipment. I leave it to the trained professionals that do this day in and day out.
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azmike

join:2012-07-19
Phoenix, AZ
reply to josephf

said by josephf:

If understanding you correctly, the original LEC from whom the number was ported-out from can interfere and stop (whether due to equipment disaster or sabotage) all callers from reaching the destination DID. This is true even though the original LEC has no customer or business relationship with either the end telephone subscriber or his current LEC.

I believe this is true in some cases. I believe "technically" the called number is looked up in an LNP database which as someone else pointed out provides an LRN. That database doesn't necessarily reside with the original CLEC. When I worked in the industry (10+ years ago) porting was not possible but was being discussed/formulated. As such I'm certainly no expert regarding SS7 today. I was just attempting to illustrate what goes on behind the scenes when a call is placed.

Iscream
Premium
join:2009-02-17
New York, NY
kudos:6
Reviews:
·Verizon FiOS

1 recommendation

reply to josephf

Don't forget that telephone is something "invented" over 130 years ago which has barely changed from its original basic "principles" during this time.

An SS7 (signaling system v.7) had been widely deployed in mid of 60's and has not changed since that either.

Moreover - a "modern" IP communication technology was also developed [by DARPA, as an aftermath of Caribbean crisis, in order to overcome possible civilization's dusk due to complete disconnection among remaining after nuclear war "islands of surviving life"] in mid of same 60's. It was greatly extended and expanded since then, but basic principles are still the same.

I'm saying this about "IP" because it works, in means of routing, much the same way as SS7. Any IP address belongs to its own, so called "portable range" sub-network. Those sub-networks are allocated and assigned to ISPs by very few global entities called Internet Numbering Regiostries - for example the one in America is called ARIN - American Registry of Internet Numbers. Another one - in Europe is called RIPE, and so on. When a portable network is assigned to an ISP - that ISP may begin announcing it via BGP4 to different Internet backbones who "spread" that information to all other interconnected IPSs and independent BGP4 peers. Then much smaller ranges, down to former Class-4 (256 addresses) or even smaller - down to a single IP address - are being assigned to ISP's customers, equipment or colocation. An ISP's customer may in turn be "multihomed" - connected to more than one ISP - then such a customer requests from its "main" (called "homing") ISP a permission to re-announce their IP allocation to its other peers (homes) - this way a network becomes "ported" to several other ISPs. I'm not going into details of this mechanism, but want to say that should a "main" ISP's router fail - all other "homes" will be screwed as well...

Even much more than one can imagine. As a matter of fact - due to "softened", "loosened" and "relaxed" regulations (or complete lack of such) for IP world - some huge IP routing disasters happen almost each year, sometimes - more than once a year. Because some ISP may mismanage their BGP4 router or routers (called Autonomous System) to begin announcing NOT their IP networks or IP ranges _wider_ than their own - to their BGP peers. Then results are unpredictable causing sometimes whole countries and continents to lose their Internet connectivity partially or completely. There are some "techno-ethical" behavioral rules for network managers as well as "techno-survivor's" rules for BGP backbone network managers, but smaller and larger IP-world-tragedies keep happening.

On an opposite side- there are virtually NO such tragedies in the telecom world. That's right - for a short time one may cause a "small" sabotage or mishandling, but that would be a last time he/she could do it. The rules of conduct are very strict in the telecom for xLECs; it's a matter of survival for a LEC - to control and prohibit any possible network management practices leading to TDM inter-network problems.

There are many books written about how telecom works - you're welcome to get your knowledge from them.


ConstantineM

join:2011-09-02
San Jose, CA

number pooling?

Do you have number pooling in New York? I know we do in California in most (or all?) area codes.

With number pooling, is there still the primary owner of the NPA-NXX, which would be distinct from the individual owners of the NPA-NXX-X? Would it at all make it easier to have the ported number work, should individual owners of individual 1k (or fewer?) blocks be completely down?



Davesnothere
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join:2009-06-15
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kudos:7
reply to Trev

Re: Do All Calls to DID Go Through Original CLEC After Ported?

said by Trev:

said by jimk:

No, it doesn't go through the original CLEC equipment.

When a number is ported, it is assigned a LRN.

The LRN looks like a telephone number but works differently.

It allows a call to be routed directly to a different provider's switch.

This has been my understanding as well, but on that token I do not work on this kind of equipment....

 
This has also been MY understanding of it.

Pay particular attention to the last paragraph on that linked page.

The LRN is the key to avoiding the original switch of the ILEC/CLEC.

For everyone's convenience....
quote:
Call Flow to a Ported Telephone Number :

When a call is made to the ported telephone number, the initiating service provider switch launches a query to its LNP call routing database to determine whether the telephone number has been ported. If it has, the database response provides the switch with the LRN needed to properly route the call. If the number is not ported, the database response indicates that the call should be routed based on the telephone number. When multiple switches are involved in the call path, the next to last carrier has the responsibility to make the LNP database query if one has not already been made.


azmike

join:2012-07-19
Phoenix, AZ

1 recommendation

So in reality this sentence:

When a call is made to the ported telephone number, the initiating service provider switch launches a query to its LNP call routing database to determine whether the telephone number has been ported.
Should say:
When a call is made to the ported telephone number, the initiating service provider switch launches a query to an LNP call routing database to determine whether the telephone number has been ported.
The reason I say that is depending upon the decisions made by the "initiating service provider" they may or may not have their own LNP database. In the case of small (underfunded) service providers - most VoIP providers - they likely do not. Instead they choose to use the LNP Database Query Service of one or more larger providers. In this case they simply pay fractions of a penny for each query, or have some other business relationship in place.

In my case I researched this process roughly a year ago because callers to my ported number were randomly receiving a recording that the "Mobile number they were trying to reach had traveled beyond the service range" or some such thing. The ported number was never a mobile number, not originally or after the port.

Turns out the company that received my ported number was using the LNP database of the original provider. In addition there was evidently some LCR (Least Cost Routing) magic that added more confusion (namely the mobile number thing). This led me to believe that the original was always involved in the process of the call with the simple purpose of obtaining an LRN. In fact this is not always true but apparently is fairly common.

azmike

join:2012-07-19
Phoenix, AZ

1 edit

1 recommendation

Oh and forgot to say...

From what I was told typically there is no initial lookup in an LNP database when a call is originated. Calls are simply processed as "normal" - that is, assuming the number has not been ported. This is the part that I don't recall 100% but I thought the original service provider would typically return an LRN if the number had been ported. If it didn't return an LRN then there was at least some other indication that it was not the "end point" for the call. Then at that point the originating switch would do the LNP lookup "song and dance".

Anyway that's why I thought the original xLEC was typically involved in at least the initial signalling part of a call.


josephf

join:2009-04-26

If your described scenario is correct, then it would appear that it takes longer to complete a call to a ported number than to complete a call to a non-ported number, due to the extra steps you described involved when the number is a ported one.



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:9
Reviews:
·SONIC.NET

said by josephf:

If your described scenario is correct, then it would appear that it takes longer to complete a call to a ported number than to complete a call to a non-ported number, due to the extra steps you described involved when the number is a ported one.

Not really. The LNP database lookup needs to be done either way (only a failure to find the dialed number in the database tells the provider that the number has not been ported).
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