Southwestern Bell Telephone Company is a wholly owned subsidiary

Subsidiary

A subsidiary company, subsidiary, or daughter company is a company that is completely or partly owned and wholly controlled by another company that owns more than half of the subsidiary's stock. The subsidiary can be a company, corporation, or limited liability company. In some cases it is a...

 of AT&T

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

. It does business as AT&T Southwest and other d/b/a names in its operating region.

The company is currently headquartered in Dallas, Texas

Dallas, Texas

Dallas is the third-largest city in Texas and the ninth-largest in the United States. The Dallas-Fort Worth Metroplex is the largest metropolitan area in the South and fourth-largest metropolitan area in the United States...

 at One AT&T Plaza

One AT&T Plaza

Whitacre Tower, also known as One AT&T Plaza, and formerly known as One Bell Plaza and One SBC Plaza, is a 37-story high-rise in Downtown Dallas, located adjacent to the Akard Street Mall....

.
The Missouri and Kansas Telephone Company was officially founded in 1882. It was consolidated under the management of a single management unit of the Bell System

Bell System

The Bell System was the American Bell Telephone Company and then, subsequently, AT&T led system which provided telephone services to much of the United States and Canada from 1877 to 1984, at various times as a monopoly. In 1984, the company was broken up into separate companies, by a U.S...

 with Southwestern Telegraph and Telephone Company of Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

-Arkansas

Arkansas

Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...

, Pioneer Telephone and Telegraph Company of Oklahoma

Oklahoma

Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

, and The Bell Telephone Company of Missouri—also called The Missouri Bell Telephone Company—on March 1, 1912.