Re: NN0 Central Office Codes

Neal McLain had written:

It didn't work out that way ...

Many NN0 codes were assigned as central office codes whenever and > wherever they were needed, without regard to their positions on Chart 5. > Examples that come to mind: > 702-870 (#3 on the list) ca. 1989 Las Vegas > 312-990 (#32 on the list) ca. 1988 Hinsdale > 201-460 (#36 on the list) ca. 1982 Lyndhurst > 414-730 (#52 on the list) ca. 1986 Appleton > 214-680 (#54 on the list) ca. 1983 Dallas

I can add, all circa 1984 from Houston: 713-520 713-630 713-840 713-850

The first two were in the JAckson switch (Montrose, River Oaks, the Museum District) and the 520 prefix is an obvious candidate for "lookalike" status. At the time, Southwestern Bell had been so regular in grouping exchanges by the first two digits that Key Maps, a local company, was able to publish maps identifying exchanges by the first two digits only in most cases.

I can personally attest to 713-630 because that was used for the PBX at KTRH radio, where I worked at the time. While most of the "public" numbers for KTRH were standard JAckson numbers -- I'm pretty sure the main call-in number was 526-5874 (KTRH) -- our internal extensions were of the form 630-3xxx.

The second two were in the NAtional office (Greenway Plaza and the Galleria area). They, of course, looked nothing like the usual

62x-xxxx numbers in that area.

Curiously (as Mark Roberts noted in TD 24:482), 530 (#1 on the list)

> was in service -- at least briefly -- in California in 1965, a decade > before Chart 5 was published.

As an interim measure, until I can write up some better-looking pages, I have put the 1964 and 1965 exchange maps online from the Pacific Bell Oakland ("East Bay") directory.

I should note that there was a *series* of maps, designed to indicate the message-unit charges from the East Bay "exchange" (Berkeley, Main-Piedmont, Alameda, Fruitvale, Trinidad) to other rate centers in the region. Each East Bay rate center had its own map. I've scanned the ones for Main-Piedmont to provide a comparison, and to more clearly show the "530" prefix in the Fruitvale area in the 1965 map.

On the map: A = Berkeley B = Main-Piedmont C = Alameda D = Fruitvale E = Trinidad

Sometime in 1965 -- I have not yet nailed down when -- there was a spinoff into a new switch, affecting primarily the Fruitvale rate center, but also the eastern part of Main-Piedmont. Approximately the eastern half of the Fruitvale rate center plus the little corner of Main-Piedmont went into the switch now known as OKLDCA13DS0. This split accounts for the new 339 and 531 prefixes. As I previously mentioned, 530 popped up only for that year. Later, however, 530 "joined" 531 in eastern Fruitvale and is an active prefix today (several of my neighbors have it including one who moved to this area in the 1970s).

Another thing I need to nail down is how extensive the cutover was at first. Today, the Fruitvale OKLACA13DS0 area extends all the way to Interstate 580 and over to the junction of 580 and Highway 13. It may be that the original cutover area was smaller, and areas were added later (e.g. along MacArthur Boulevard).

This distinction, of course, is NOT shown on the maps that I scanned, and consequently will have to be inferred from listings, newspaper ads, etc.

Anyhow, here are the maps. There were several prefixes added between

1964 and 1965, not just in Oakland:

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Mark Roberts | "I know you know the situation is past critical." Oakland, Cal.| -- FEMA staff member Marty Bahamonde, in New Orleans NO HTML MAIL | "Anything specific I need to do or tweak?" | -- FEMA director Michael Brown replies to that e-mail

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Mark Roberts
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