Reader Britta (who also a few weeks ago dug up all that info on the old police station on 17th) dug up all the info and made a LocalWiki article about it:
In a residential area at Capp and 25th in the Mission, there’s an oddly big office building that always has lights on at night. What is that? It’s the telco building at 3333 25th Street, owned by AT&T.
In other words, it’s a telephone exchange containing telephone switches and other pieces of equipment, called a “central office” in telecommunications company jargon.
Read on for lots more info and history. Thanks, Britta!
UPDATE: Oh doy! Commenter sfnola says, “This is where The Phone Booth at 25th/SVN gets its name.” Nice.
 dug up all the info and made a LocalWiki article about it: In a residential area at Capp and 25th in the Mission, there’s an oddly big office building that always has lights on at night. What is […]</p>
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Yes- this is where The Phone Booth at 25th/SVN gets its name.
They built these everywhere, back when they were still Bell Telephone. Usually they’re huge and windowless. I think there’s another in the Sunset around 20th & Kirkham, bet there are a few more around the City.
This site says there are four Pacific Bell central offices in San Francisco: http://www.thecentraloffice.com/calif/SFO/San%20Francisco.htm – it doesn’t mention any in the Sunset. Maybe there’s something else out there?
There it is folks, the very building where all of your data is mined by the NSA.
AT&T’s Folsom Street building is the one infamous for having a room for the NSA to intercept internet traffic: https://en.wikipedia.org/wiki/Room_641A
“The Hellmouth” is that monstrosity’s name in our house a block away. It funnels cold air rolling off Bernal into a hat-flipping umbrella-flattening tempest. Somebody should setup a windmill. (And that’s before it casts its giant dark shadow across our hood.)
Not very useful fact: the phone on the gate of this building is a functioning free public telephone if you happen to need one.
This picture: http://timelifeblog.files.wordpress.com/2014/07/140728-san-francisco-39.jpg from 1969 shows the building, already at eight stories, so it must have been in 1947 when they increased the height from three. Different times, different zoning laws… (From http://bernalwood.wordpress.com/2014/08/13/lets-explore-life-magazines-mysterious-1969-photo-on-bernal-hill/ )
Is it not possible that the Pac bell building referred to in the 1909 entry is (or was) the 1045 Capp structure, which might have been 3 stories tall at the time?
The 25th/Capp structure looks like something built in the ’50s and may have first added to and later replaced the other location.