I know this post is a bit old, but I thought there might be some interest in what a quick hour of research was able to dig up in the Oakland History Room of the Oakland Public Library ...
Anthony Bellanga had written:
I have been able to nail it down, for the East Bay at least, to sometime between 1946 and 1948. I can't get any closer because the telephone directory for 1947 was not available.
For those of you who are interested, here are some of my notes. I originally did this to research some oddities we have here with respect to rate center-switch combinations. Note especially the strange appearance of the "530" prefix in 1965 and the "911" service code in brief use after WWII.
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Directories available - 1935, 1944, 1946, 1948-53, 1958-66.
The 1954-57 gap is a key gap. This appears to be when dial service was fully implemented.
From 1960 or 1961, the list of exchange names and rate centers, all of which are extant today unless indicated otherwise:
Main-Piedmont [need to get third digit]: ------------- CRestview GLencourt HIghgate OLympic TEmplebar TWinoaks
Alameda --------- LAkehurst
Berkeley -------- AShberry (gone) CEdar (gone) LAndscape THornwall
Fruitvale --------- ANdover KEllog (yes, one g)
Trinidad (includes San Leandro) -------- ELgin LOckhaven NEptune SWeetwood TRinidad
Contra Costa County exchanges that were local calls: Orinda - CLifford Lafayette - ATlantic Walnut Creek - YEllowstone Moraga - DRake Concord - MUlberry
Contra Costa phones appeared not to be dial into 1953 according to instructions in the local calling guide.
Montclair phone numbers:
Phone numbers in the hills changed between May 1964 and June 1965 directory. This must have been when OKLDCA13 was built. Main-Piedmont rate center (e.g. most of Montclair business district) changed from OLympic numbers to 339. Fruitvale rate center (Montclair Methodist Church, areas S of Snake Road/ Shepherd Canyon Road, i.e. the old ROW for the Sacramento Northern railway) changed from ANdover or KEllog numbers to 531. I should have checked to see if there were similar changes in the Glenview, Oakmore, Dimond, or Laurel Districts.
Probably so. Imagine the huge effort it took to cut phones over to a different switch!
=> In the 1965 directory, *two* new prefixes were listed in the local calling pages for the Fruitvale rate center: 531 **and** 530!
In the 1966 directory, only 531 was listed. I did not see any phone numbers with 530 listed in the 1965 directory. Years later, of course, 530 was added to the Fruitvale-OLKDCA13 rate center-switch combination.
Did someone at Pac Bell jump the gun? This is the earliest I have ever seen a prefix of the form xx0.
Dial service and numbering schemes:
Phone numbers were six digits (2L-4N) in 1935. There is no clear indication as to which numbers were dial and which were not other than "J" or "W" suffixes. Interestingly enough, 211, 411, and 611 service codes were already established for dial phones. No DDD, of course. One-page, bare-bones introduction. Opening a 70-year-old phone directory is a great way of generating sneezing fits. The Bell Gothic typeface was not in use at this time.
The 1935 directory also included just about *every* Bay Area community. Oakland-Piedmont-Berkeley-Alameda were listed first, then the business directory, then San Francisco, then San Mateo and San Jose.
By 1944, there was mixed 2L-4N and 2L-5N numbering. Unclear, but it appears that 2L-5N phones were always dial phones. Occasionally 2L-4N numbers appear with "J" or "W" suffixes. Bell Gothic typeface in use.
In 1946, "911" was used as a service code for dial phones to reach Hayward telephone numbers.
The 1947 directory is missing. By 1948, all phones were 2L-5N. "J" and "W" suffixes were retained. Most notably, this was for the "BErkeley" exchange (BErkeley 7, would have been "237" had it survived) and "PIedmont" (PIedmont 5, would have been "745" had it survived).
Also by 1948, "911" disappeared as a dialing code for Hayward but instead was a dialing code for LAndscape numbers (Berkeley) to reach Richmond numbers.
By 1948, apparently BErkeley, AShberry (3), PIedmont, and HUmboldt (3) were operator-assisted exchanges. Montclair phones in Main-Piedmont rate center were mostly PIedmont numbers. But it may have been a mixed dial-operator area, because there were a few OLympic 2 or OLympic 3 numbers by then. Montclair phones in the Fruitvale rate center were dial.
By 1958, PIedmont, AShberry, BErkeley all were gone as exchanges. (N.B. There's a key gap here because the 1954-57 directories are missing or not available.)
The last year that 2L-5N numbers were used exclusively was 1960. Local dialing guide shows one 7N prefix in 1961 (849), but individual listings still were shown. Oddly, some listings showed only the letter prefix (OL) while others showed the full name (OLympic). Users were advised to look up the full prefix name on a page in the front. Was this due to production limitations (after all, we're talking hot metal typesetting here!)?
A few more 7N numbers (3N prefixes) showed up in 1962. Where applicable, though, individual listings showed the 2L prefix, either in the short form or as full name.
The May 1963 directory was the first to list all numbers in the 7N form. The local calling guide still listed prefix names where applicable.
The May 1964 directory listed only the 2L prefix abbreviation, and not the full prefix name in the local calling guide.
The June 1965 directory is the first one to show the realigned numbers in the hills.
The local calling guide is missing from the June 1966 directory, but approximately half the list of rate centers and message unit charges still is extant.
Long Distance
There's an odd statement in May 1964 directory in the area code listings, "To make a direct Distance call, just dial the Area Code and then the telephone number". Does that mean no "1" or "211" was used?
The 1960 directory gives "211" as the Long Distance number but some (not all) locations could be direct dialed.
It appears that they could dial each other 2L-4N in 1935, as indicated above.
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