140 New Montgomery Street is a 26-floor Art Deco mixed-use office tower located in San Francisco's South of Market district, close to the St. Regis Museum Tower and the San Francisco Museum of Modern Art. Constructed in 1925 as a modern headquarters for The Pacific Telephone & Telegraph Co., it was originally known as The Pacific Telephone & Telegraph Company Building or simply the Telephone Building, and, after 1984, as The Pacific Bell Building or The PacBell Building.

The Pacific Bell Telephone Company (Pac Bell) is a telephone company that provides telephone service in California. The company is owned by AT&T through AT&T Teleholdings, and, though separate, is now marketed as “AT&T”. The company has been known by a number of names during which its service area has changed. The formal name of the company from the 1910s through the 1984 Bell System divestiture was The Pacific Telephone and Telegraph Company. As of 2002, the name “Pacific Bell” is no longer used in marketing, although Pacific Bell is still the holder of record for the infrastructure of cables and fiber through much of California.