AUGUSTA — AT&T says customers in Kennebec County can expect improved mobile broadband coverage and voice performance as a result of continued upgrades to its network.

The company said changes will be noticed in Augusta, Litchfield, Monmouth, Manchester, Oakland, Waterville, Winthrop and West Gardiner.

The network enhancement adds new layers of frequency, also known as carriers, to cell sites across Kennebec County to more efficiently manage available spectrum and increase mobile broadband capacity, the company said in a news release.

AT&T, which is battling to acquire T-Mobile USA — which has a major customer call center in Oakland — made $60 million in investments in its Maine wireline and wireless networks from 2008 to 2010, the company said. This year, AT&T said it has added seven new cell sites in Maine and added capacity to nearly 150 cell sites.

“Our recently announced agreement to acquire T-Mobile USA will strengthen and expand our network in the Kennebec County area,” said Steve Krom, vice president and general manager for AT&T New England. “If approved, this deal means that we’ll be able to expand the next generation of mobile broadband — 4G LTE — from our current plan of 80 percent of the U.S. population to more than 97 percent.”