Applied online, got called by a staffing manager a week later who wanted to verify my interest, We set up a phone interview for later the same week with a hiring manager. The hiring manager called right on time. The interview had very few technical questions (all of which pertained to experience with Office), and mostly personality. I didn't think it went very well, but I got called back the following week to schedule a 1:1 interview for the week after that. Went to the interview, mostly personality again with a more detailed description of the program. I thought this interview went very well, but I wasn't selected out of the 4 people competing for the position.

Two phone interviews, mostly a character evaluation, with some emphasis on relevant engineering projects. Very stress free, they are mostly giving you a breakdown on how the intern program is conducted, with opportunities to meet with many different department heads at AT&T. They mostly are interested in your excitement for the role.