TELECOM Digest OnLine - Sorted: Re: Telephone Exchange Usage in Low-Volume States

Re: Telephone Exchange Usage in Low-Volume States
Wed, 17 Aug 2005 17:43:42 -0400

Neal McLain wrote:

> In order to accommodate inbound DDD, it was essential that every
> number have a 7-digit format. But SxS switches couldn't accommodate
> 7-digit dialing, so telcos faked 7-digit numbers by prepending dummy
> digits. Local calls continued to be dialable with only four or
> fivedigits; however, if a local caller actually dialed all seven
> digits, the prepended digits were absorbed by "absorbing selectors" --
> i.e. ignored.

I don't understand. Below is the local dialing plan we had when I was
in school.

Carbondale, IL, (Jackson County) 1971 General Telephone

618-453 - So. Il. Univ., Carbondale. IL
618-457 - Carbondale, IL
618-549 - Carbondale, IL
618-867 - De Soto, IL
618-684 - Murphysboro, IL
618-687 - Murphysboro, IL

From/to any Carbondale NXX (1, 2, or 3): 5-digits allowed, 7-digits
supported (618-453 required a ?9? to dial out from the university, but
5-digits allowed within the university PBX/Centrex/whatever)

From Carbondale NXX (1, 2, 3) to De Soto (4): 7-digits required

From Carbondale NXX (1, 2, 3) to Murphysboro, (5, 6): 7-digits required.

From Murphysboro or De Soto to Carbondale, 7-digits required.

(I believe that locally, only 5-digits were required in Murphysboro
and only 4-digits in De Soto.)

Outside of these 3 exchanges, but within the 618 NPA: 1+7-digits
required Outside the 618 NPA: 1+NPA+7-digits required

Carbondale had DDD in the 60's. It did use '150' instead of just '1'
as a toll alert and the operator would come on the line and ask 'Your
Number Please?'

Date: 18 Aug 2005 02:26:35 -0000
From: John Levine <>
Newsgroups: comp.dcom.telecom
Subject: Re: Telephone Exchange Usage in Low-Volume States
Message-ID: <>
Organization: I.E.C.C., Trumansburg NY USA
X-Telecom-Digest: Volume 24, Issue 373, Message 7 of 10
Lines: 28

> Could you elaborate on the situation in "the most remote areas"? Has
> it been cost effective to replace an isolated long loop shared party
> line with more modern carrier equipment?

Yes. My relatives' telco in Vermont has some really long loops out to
remote farms, and they're all private lines. The maintenance is a lot
easier, as is the toll billing. They have a Paradyne DSL system that
works on long loops and they told me about one farmer who wanted DSL
so they took him off the SLC which didn't support DSL and gave him an
18k ft home run so the 60 hz hum on voice calls was deafening but the
DSL works fine.

> In many places the demand for exchanges is so high that the only way
> to create unique dialing is require TEN digits. But in the states I
> mentioned perhaps there is enough 'space' in the exchange assignments
> that five digits could still be unique for a town.

Sure, but for policy reasons dialing is now all 7D or 10D or 1+10D.
There is exactly one prefix in my town, and we tell each other our
phone numbers with four digits, but the dialing is 7D nonetheless.
It's 7D within the area code, which may be local, intralata toll or
interlata toll, 1+10 to other area codes.



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