AT&T, the No. 2 U.S wireless provider, has been exploring options to pay down its debt and raise funds for investments in recent months. The company declined to comment.

The three sources requested anonymity because the matter is not public.

AT&T and its rival Verizon have been selling non-core assets in recent months. Verizon is close to announcing divestitures of wireless towers and wireline markets worth $10 billion, the Wall Street Journal reported on Monday.

AT&T hired a financial adviser to assist in the sale.

Following spectrum investments and pending acquisitions, AT&T's debt ratio may rise in the near term, the company said last week after spending close to half of the total bids in the record-setting $44.9 billion spectrum sale that concluded last week.

AT&T emerged the top bidder in the AWS-3 spectrum auction by bagging 251 licenses worth $18.2 billion.

The company has also been investing to expand its footprint in Mexico to grow its business, as the U.S. wireless market reaches saturation. It said last month it would buy bankrupt NII Holdings Inc.'s wireless business in Mexico for $1.875 billion.

AT&T also sold its wireline operations in Connecticut to regional telephone operator Frontier Communications for $2 billion in late 2013 to raise cash for network upgrades.

In 2013, AT&T completed a $4.85 billion sale of some of its towers to tower operator Crown Castle and preserved its right to lease and operate them for about 28 years.

The Wall Street Journal first reported AT&T's plans to sell its data centers on Monday.