The Pacific Telephone and Telegraph Company managed the Bell System's telephone operations in California. It grew by acquiring smaller telephone companies along the Pacific coast.

It built and occupied San Francisco's Pacific Telephone Building on New Montgomery Street which has been described as a "monument to western progress and foresight".

Prior to the AT&T breakup in 1984, AT&T held 89.8% of Pacific Telephone.

After the breakup, The Pacific Telephone and Telegraph Company changed its name to the Pacific Bell Telephone Company, or PacBell for short. Pacific Telesis was formed as a holding company for PacBell's interests, with PacBell and Nevada Bell (which PacBell had owned since 1913) as its operating companies.gional Bell Operating Companies.

Since Nevada Bell had long been a PacBell subsidiary, that company was omitted from the Modification of Final Judgment that broke up the Bell System.