It wasn't too difficult overall. It went phone screen -> coding challenge -> on-site, as with many other companies. The interviews were pretty easy. They're looking for charismatic people who have the ability to communicate well and know CS fundamentals.
Computer Science fundamentals - nothing too tricky, make sure you know the basics of the language you're most comfortable in.
Knowledge of OOP, simple data structure questions.
The following metrics were computed from 31 interview experiences for the AT&T Software Engineer (Internship) role in United States.
AT&T's interview process for their Software Engineer (Internship) roles in the United States is fairly selective, failing a large portion of engineers who go through it.
Candidates reported having very good feelings for AT&T's Software Engineer (Internship) interview process in United States.