CenturyTel Inc. said Thursday that it will buy Qwest Communications International Inc. in a stock swap worth $10.6 billion, creating a telecommunications giant serving customers in 37 states, the Associated Press reports. The deal unites the third and fifth-largest telephone companies in the U.S. by number of traditional phone lines.

Together, they’ll have about 18 million phone lines.

Qwest is one of Colorado’s largest employers. The employment effect wasn’t immediately known.

Update: The combined company will be based in Monroe but will have a “key operational presence” in Denver, Marketwatch reports.