From: varney@ihlpf.att.com (Alan L Varney)
Newsgroups: comp.dcom.telecom
Subject: Re: Why Four-Digit Carrier Identification Codes?
Date: 13 Sep 92 00:00:00 GMT
Organization: AT&T Network Systems, Lisle, IL
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X-Telecom-Digest: Volume 12, Issue 707, Message 1 of 7

In article <telecom12.699.10@eecs.nwu.edu> sequent!islabs!fasttech!
zeke@uunet.UU.NET (Bohdan Tashchuk) writes:

> Several recent messages have mentioned there will soon be a change
> from three-digit to four-digit long distance carrier identification
> codes.  Why is this change necessary?

> I've only ever had a use for three different codes: 10222, 10288, and
> 10333.  I'm sure that sophisticated users need many more than this,
> but are four digits really necessary? Is there a reluctance to re-use
> old codes freed up because of mergers, bankruptcy, etc?

   Well, I only use a hand full of NPAs, but that doesn't mean we
aren't running out of them :-) The change is needed for the obvious
reason: Most XXX codes are already assigned, and (unlike
electromagnetic spectrum) the FCC doesn't want to limit the number of
competitors in "telecom" by limiting a resource (the XXX codes).

   Prior to divestiture, the original Carrier Interconnect
requirements specified provisions for 100 ICs (00 to 99) -- no one
really thought there would be more companies than this actually
running cable/fiber and buying switches, etc.  Late in the
requirements phase, the Carrier Access Code went to three digits.
There was an explicit binding of 950-WXXX and 10XXX numbers to the
same carrier.

   So what happened?  Are we lousy planners?  Well, maybe.  Several
factors have emerged to change the "IC" marketplace, and "use up" the
XXX codes -- (I'm sure Bellcore (as the NANP Administrator) could give
you even more reasons!):

  1) An IC doesn't have to own switches or networks or anything other
than an XXX code, some billing system and (maybe) some trunks -- they
can get an XXX code, contract with a "real" IC for service, and hope
to profit from the IC's "bulk" rates or other discount arrangements.
While this was mentioned as a possibility in discussions, I (and
others) didn't believe there would ever be enough economic leverage to
make this a "common" practice.

  2) It was imagined that regional carriers could exist and that XXX
codes could be assigned on a regional basis -- 10999 could be New
England Oil and Telephone Co. in one area and Southern Beer and Telco
in another.  The reality was that no carrier would ever want to
restrict itself to one region -- what if it were wildly successful
(wants to grow) or not (junk bond candidate for non-regional
takeover).  No one wants to share what might be a valuable asset (an
XXX code).

  3) The "interim-only" access via 950-WXXX was tariffed in a way that
attracted non-ICs (other Service Providers, etc.).  This used up a lot
of XXX values.  Those XXX values couldn't be shared with a 10XXX-only
carrier, because the 950 customer didn't want to share either.

  4) Several ICs have requested multiple XXX codes, to allow service
identification based on the code.  This was partly the result of a
failure to develop another means of service identification and the
means to assign "generic" service codes and simultaneously allow
carriers to invent new services without negotiating service codes in a
public arena (and thus divulging the service to the competition
early).  Bellcore's position is that neither NPAs nor XXXs should be
used for identification of services or facilities -- but the
alternative mechanisms appear to be either inadequate or inconvenient.

  5) Mergers/buy-outs don't result in freeing up of XXX codes -- the
customer base doesn't want to change their dialing habits or PICs, the
rates might vary by XXX code (even though a single IC carries the
traffic), and again -- why give up an asset?  Use it or LOSE it!

> How soon will this change occur? Will it be in an upward-compatible
> fashion?  Will I still be able to dial 10ATT when I need to avoid AOS
> scum?

   Short answers:  1995, of course, sure -- but maybe not forever.

   If you're really interested in the details (as in willing to part
with $35), Bellcore's TR-NWT-001050 has specifics on the transition
capabilities to be supported by switches.  The Carrier Liason
Committee and it's sub-committees (NOF, ICCF, etc.) have planned a
mid-1995 deadline for deployment of the expanded "capability" in
RBOC/GTE switches.  That's early enough to meet the worst-case needs
for accessing the first XXXX carrier.  When customers will actually be
able to "dial" that carrier will depend on the actual need.  The TR
supports a phased approach in XXXX assignment that allows for growth
to 2970 XXXX codes, and later (if needed) to 10,000 codes.

   Note that prior to this capability, TR-TSY-000698 had already been
updated to allow FG-B signaling and 950-access to support 10,000
FG-B-only carriers -- that is, 950-XXXX was supported with only the
original 950-0XXX and 950-1XXX ranges having a "transition to FG-D
signaling" capability.  This was in place around mid-1991.

   Briefly, for FG-D signaling and 10XXX access, the phases are:

1) Deploy switches, databases, operations systems, billing systems,
etc.  the support XXXX codes in all the internal communication paths
(switch output messages, AMA records, SMDR, SCPs, etc.)

2) Convert inter-switch trunks (EO to AT, EO/AT to IC for
International) to signal four-digit XXXX codes where-ever three was
used before.

3) Enter the "permissive" dialing phase, where 10XXX still works for
XXX values other than 1XX.  For other codes, 101XXXX becomes the
Carrier Access Code.  This period may last for a LONG time (my
opinion).  1010XXX also works to reach the old three-digit carriers.

4) Enter the "post-permissive" dialing phase, where 101XXXX must be
used to access all FG-D carriers.  Carriers with old XXX codes will
automatically receive 0XXX codes.  Only at this point will Bohdan and
others be required to dial "1010288" in place of "10288".


Al Varney -- this is my opinion today -- I might change it tomorrow!