From a letter from the agency to AT&T:
We appreciate your efforts to respond to the Information and Discovery Requests sent to you on June 5, 2013, which, among other things, requested AT&T’s plans for migrating all of ATN’s customers following the proposed transaction. In response, we have received information on AT&T’s plans for ATN’s post-paid customers. As of the date of this letter, however, despite several Commission staff follow-up conversations about the importance of transitioning pre-paid customers, we have received no detailed responses from AT&T on its plans for transitioning ATN’s significant pre-paid customer base
AT&T issued their own statement to the press on the matter:
“AT&T is extremely disappointed at the FCC delay today on this small transaction. AT&T is ready, willing, and able to make significant network investments in these rural territories to bring HSPA+ and LTE services to Allied’s customers, an investment that will not occur but for this transaction. AT&T has actively worked to address FCC concerns and will continue to work with the Commission until all issues are resolved.”
The chunk of Alltel being acquired by AT&T was what remained after Verizon acquired the majority of Alltel back in 2008.