[VoiceOps] Ambiguous dial plan pattern matching

Tue Dec 4 16:00:37 EST 2012

I tested my home phone by dialing a string of 2s of varying length and measuring the PDD in seconds.

LEN        PDD
6             20
7             5
8             20
9             20
10           0
11           can't dial 11 2s, the switch makes a decision on the 10th one.

All that fancy-pants EAS/LATA/LERG/LCAD stuff has to ultimately get implemented by something that watches every key press.  No magic, just a switch big enough to implement timers and a pile of conditional statements on every key press.

I'm sure that someone could build a SIP phone that could duplicate the digit analysis behavior of a traditional class 5 switch, but I'm not so sure that it'd be cheap enough to sell.

David

From: voiceops-bounces at voiceops.org [mailto:voiceops-bounces at voiceops.org] On Behalf Of Carlos Alvarez
Sent: Tuesday, December 04, 2012 09:23
To: voiceops at voiceops.org
Subject: Re: [VoiceOps] Ambiguous dial plan pattern matching

Mary Lou, you write some fantastic educational posts on this list.  I wanted to thank you for the time and effort you put into it.

On Mon, Dec 3, 2012 at 4:14 PM, Faisal Imtiaz <faisal at snappydsl.net<mailto:faisal at snappydsl.net>> wrote:
Thanks for an excellent detailed explanation.
:)

Faisal

On Dec 3, 2012, at 5:21 PM, "Mary Lou Carey" <marylou at backuptelecom.com<mailto:marylou at backuptelecom.com>> wrote:

> Routing is determined by the NPA type of that area AND by the local calling
> guide established by the LEC. Everyone can set their own local calling areas
> as far as rates are concerned, but you will be charged CABS according to the
> way the LEC established their local calling area for each rate center. (Rate
> centers are established by the NANP and can be a city, a portion of a city
> or a group of cities. They are listed in the LERG, and on several other
> websites such as localcallingguide.com<http://localcallingguide.com>, nationalpooling.com<http://nationalpooling.com> and nanpa.com<http://nanpa.com>).
>
> Seven digit dialing is only used in areas where there is one NPA for the
> local area. Ten digit dialing is used in areas where there is an overlay
> (more than one NPA per local area) and 11 digit (1 plus) is used in areas
> where there was an area code split. The difference between a split and an
> overlay is that a split required everyone (existing and new end users) to
> change their NPA to the new area code. Overlays allow you to assign numbers
> from the new NPA to new end users but allows the existing end users to keep
> their old NPA.
>
> LECs typically break up their local and EAS calling areas by rate center and
> while local calling areas are limited by rate center boundaries, local
> calling areas can vary by rate center. For example, someone in Nashville TN
> can make a local call to both Murfreesboro and Franklin, but a person in
> Murfreesboro cannot make a local call to someone in Franklin.
>
> Every NPA-NXX is assigned to a specific rate center and a specific switch. A
> switch can cover multiple rate centers and local calling areas, so the LECs
> set up call scenarios that detail the dialing requirements and how the call
> will be routed. They begin by adding every NPA-NXX-X associated for that
> particular switch and map out which NPA-NXX combinations require 7 digit
> dialing. Then they set up a scenario for each call type determined by route.
> So if your end user calls another one of your end users in the same rate
> center, it's going to use scenario A in which the switch will route the call
> directly itself and only require 7 digit dialing. If your end user calls
> someone on the B list (let's say that list contains all the NXXs within the
> same NPA), then require 7 digit dialing and route the call to the local
> tandem trunks. I could go on and on, but basically the concept is that after
> you determine the dialing requirements for each rate center your switch
> covers in a particular LATA and the available routes the call has to take,
> you set up call scenarios in your switch to cover each dialing requirement /
> route combination your switch will encounter.
>
>
> Mary Lou Carey
> BackUP Telecom Consulting
> marylou at backuptelecom.com<mailto:marylou at backuptelecom.com>
> Office: 615-791-9969 x 2001<tel:615-791-9969%20x%202001>
>
>
>
>
> -----Original Message-----
> From: voiceops-bounces at voiceops.org<mailto:voiceops-bounces at voiceops.org> [mailto:voiceops-bounces at voiceops.org<mailto:voiceops-bounces at voiceops.org>]
> On Behalf Of Nathan Anderson
> Sent: Monday, December 03, 2012 10:55 AM
> To: 'voiceops at voiceops.org<mailto:voiceops at voiceops.org>'
> Subject: [VoiceOps] Ambiguous dial plan pattern matching
>
> Sorry for what probably will end up sounding like a rather noob-ish
> question, but I still consider myself a relative greenhorn...
>
> We are a VoSP.  With the advent here in the U.S. of area code overlays,
> 10-digit dialing, and even carriers/vendors (VoIP and wireless, mostly)
> continuing to blur the distinction between local and toll calls (at least
> from the end-user's perspective), it is not an uncommon thing to run into
> service platforms where both 7- and 10-digit dialing is supported, but the
> 7-digit support feels (again, from the customer's perspective) half-assed,
> at least compared to the ILEC's implementation.  But if the customer still
> lives in an area where 10-digit dialing is not mandatory, he/she expects it
> to work, so we "have" to provide it.
>
> It feels inferior because back when when local destinations were always
> within the same NPA as the caller, the number pattern rules were simple, at
> least for domestic calls: if it starts with a 1, it will be an 11-digit
> number, and if it starts with 2-9, it will be a 7-digit number; but now, if
> it starts with 2-9, it could be either 7 or 10 digits, and you won't know
> for sure which one it is unless the caller has entered more than 7 digits.
> And in these ambiguous scenarios where two destination patterns partially
> overlap, it's the "did the caller stop dialing" part that's hard to measure,
> right?  So now you have CPE gear generating dialtone (whether PBX or ATA)
> which either feels to the caller like it is extremely slow at putting the
> call through, or which requires the caller to remember to do something
> special at the end of a 7-digit destination (like dial # or something to
> signal they're done) if they don't want to wait.  (There's also been a
> similar phenomenon for a whil!
> e with PBX systems that use outbound routing prefixes like '9' in order to
> make it unambiguous whether you are dialing an internal extension or an
> external destination.)
>
> Now obviously the CO switch can't read minds either, so in areas without
> mandatory 10-digit dialing, it seems inescapable that it would have to
> determine whether the user is done dialing via some kind of timeout
> mechanism as well.  But it sure seems like most Class 5 switches must have a
> much more intelligent ambiguous number pattern matching algorithm than most
> CPE gear does since, as a general rule, people that still have an analog
> loop to the CO these days and regularly dial 7 digits don't experience
> (e.g.) upwards of a 5-second delay between when they've finished dialing and
> when they hear their first ringback.
>
> The question is, what's the secret sauce, and why can't that same algorithm
> be implemented in CPE gear?
>
> --
> Nathan Anderson
> First Step Internet, LLC
> nathana at fsr.com<mailto:nathana at fsr.com>
> _______________________________________________
> VoiceOps mailing list
> VoiceOps at voiceops.org<mailto:VoiceOps at voiceops.org>
> https://puck.nether.net/mailman/listinfo/voiceops
>
> _______________________________________________
> VoiceOps mailing list
> VoiceOps at voiceops.org<mailto:VoiceOps at voiceops.org>
> https://puck.nether.net/mailman/listinfo/voiceops
>

_______________________________________________
VoiceOps mailing list
VoiceOps at voiceops.org<mailto:VoiceOps at voiceops.org>
https://puck.nether.net/mailman/listinfo/voiceops

--
Carlos Alvarez
TelEvolve
602-889-3003

This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/voiceops/attachments/20121204/1edd4126/attachment-0001.html>