30 Years of the Digest ... founded August 21, 1981
The Telecom Digest for September 20, 2011
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Date: Sun, 18 Sep 2011 21:58:23 -0500 From: Neal McLain <firstname.lastname@example.org> To: email@example.com. Subject: Re: EXchanges (was: area code named beer) Message-ID: <4E76AFCF.firstname.lastname@example.org> HAncock4 <withh...@invalid.telecom-digest.org> wrote: > On Sep 16, 7:15 pm, t...@panix.com (Thor Lancelot Simon) > wrote: >> Not such a major undertaking. In roughly 1980 I lived in a >> rural area of New York State that still had 4 digit dialing. >> Extension to a longer number can be done automatically -- >> it is fully deterministic, you are just adding predetermined >> digits. >> My number was 687-XXXX for external purposes, but for in-town >> callers, simply XXXX would do. The "687", obviously, was >> just added onto the front when numbers went to 7 digits -- >> and there were towns near us with switches still configured >> to allow 3-digit dialing, which had had four digits prefixed >> to the front, too. > If someone's phone number was say 6235, how would the switch > know if someone was dialing 687-6235 or just 6235? Most probable answer: there were no numbers in the form 6XXX, 7XXX, or 8XXX. As I explained in my post of Sep 17, 10:14, the dialing plan segregated local 4-digit numbers from the absorbed digits 6, 7, and 8. Thus: 1 = access for non-local numbers + vertical service codes 2XXX = local number, blank level, or nearby community 3XXX = local number, blank level, or nearby community 4XXX = local number, blank level, or nearby community 5XXX = local number, blank level, or nearby community 6 = absorbed at the first selector by "AR" digit absorber 7 = absorbed at the first selector by "AR" digit absorber 8 = absorbed at the first selector by "AR" digit absorber 9XXX = local number, blank level, or nearby community 0 = operator (or access code) But, as I noted previously, the above dialing plan is just a best-guess on my part. I assume Thor will let us know which levels actually were used for local numbers. As for Thor's original statement, "Not such a major undertaking," it would been a fairly straightforward undertaking at the local exchange level. Each first selector would have to have been equipped for digit-absorbing circuitry, and strapped to absorb the specific digits relevant to the exchange (6, 7, and 8 in this case). The really major undertaking would have been at the area-code level, where the job was to assign each community within the area code one or more NNX exchange codes which: - Wouldn't conflict with the local dialing plan. - Wouldn't conflict with the local dialing plan of any neighboring community reached by seven-digit dialing. - Wouldn't conflict with any existing NNX codes within the area code. - Were true NNX codes (which excludes N0X and N1X codes, which didn't exist until the '70s, and even then were restricted to larger cities already using seven-digit dialing plans). In a later message in this tread, tlvp <mPiOsUcB.EtLlL...@att.net> wrote: > On Sat, 17 Sep 2011 10:14:40 -0500, Neal McLain wrote: > ... [big snip] ... >> John figured out that if he asked the operator for 8-2440, >> the operator would dial it like any other 8-XXXX number. >> He'd then flash of the switchhook on his room phone, >> effectively dialing 1. Thus, the central office saw 82-4401, >> ignored the "A"-digit 8, and sent the call right back to the >> West Quad PBX. John could make an inside call. > Hook-flash dialing was quite a trick to master, if you hadn't > quite ever needed to before. Well, yeah, but if you're only dialing a 1, it's pretty easy! The trick is to do it fast enough that the CO won't hang up, and that it won't attract the attention of the PBX operator. Neal McLain
Date: Mon, 19 Sep 2011 16:46:05 -0700 (PDT) From: Wes Leatherock <email@example.com> To: firstname.lastname@example.org. Subject: Re: EXchanges (was: area code named beer) Message-ID: <1316475965.50015.YahooMailClassic@web111716.mail.gq1.yahoo.com> --- On Sun, 9/18/11, Neal McLain <email@example.com> wrote: > > The really major undertaking would have been at the > area-code level, where the job was to assign each community > within the area code one or more NNX exchange codes which: > > - Wouldn't conflict with the local dialing plan. > > - Wouldn't conflict with the local dialing plan of any > neighboring community reached by seven-digit dialing. > > - Wouldn't conflict with any existing NNX codes within the > area code. > > - Were true NNX codes (which excludes N0X and N1X codes, > which didn't exist until the '70s, and even then were > restricted to larger cities already using seven-digit > dialing plans). A list of prefixes was assigned for each area code, and all of those considerations were taken into account when the list was first set up. Prefixes were not just assigned randomly. In locations which already had multiple prefixes, those were incorporated into the first area code-wide assignment. There were also some locations where a community of interest existed between offices in different area codes, where the prefix had to be "protected" in both area codes. A prime example was the greater Kansas City Metropolitan exchange, since the metro area extended across two states with seven-digit dialing. The Missouri side had area code 816, the Kansas side 918. Of course, this consideration ceased to be a factor when mandatory 10-digit (or 11-digit) dialing on local calls came into existence. Wes Leatherock firstname.lastname@example.org email@example.com
Date: Mon, 19 Sep 2011 16:59:14 -0400 From: tlvp <mPiOsUcB.EtLlLvEp@att.net> To: firstname.lastname@example.org. Subject: Strange new at&t rumors Message-ID: <email@example.com> In http://www.zdnet.com/blog/btl/at-t-moves-on-to-last-ditch-efforts-to-save-t-mobile-deal/58351?tag=nl.e550 today: "AT&T is reportedly trying to sell off subscribers and spectrum to smaller regional carriers to save its proposed bid for T-Mobile." Editorializing, ZDnet suggests, "It looks like the idea is that AT&T wants to appear like it has less coverage and lacks the resources to expand to justify the need for acquiring T-Mobile and its nationwide network - the fourth largest in the country - which is what AT&T has been arguing all along." I'm just left scratching my head ... and wondering what my future as an erstwhile T-Mobile customer is going to become. Cheers, -- tlvp -- Avant de repondre, jeter la poubelle, SVP.
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