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AT&T interview notes, page 1 of 6

Large Enterprises

Most of these AT&T write-ups come from Software Engineers (56), then Data Scientists (1). The most reported rounds are the technical phone screen (15), the hiring manager screen (14), the system design round (7) and the multi-round onsite (6).

57 interview notes · updated Oct 2026

AT&T·Software Engineer·Onsite - Multi Round

Jul 2024
Eight-plus years in infra and distributed systems, ten onsites between March and July, one offer. The funnel was brutal at every stage and even walking out of interviews feeling good didn't mean much in a pool this competitive.
  • How do you think AI will change this space going forward, and what's your experience with it in production?

“This is the one that probably cost me the offer.”

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AT&T·Software Engineer·Executive / Final Round

Nov 2025
Went through multiple intern application cycles with a 3.7 GPA and solid hardware/software projects, got maybe 4 interviews total across two seasons, made it to the final round at a defense contractor but froze on the whiteboard and didn't get the offer. The recurring feedback: great resume, just no experience.
  • Do you know C++? (and similar basic skills-verification questions asked verbatim from an application form)
  • Whiteboard coding problem during a final-round in-person interview at a defense contracting company.

“Two of my four interviews were HR reps who straight up told me they had never interviewed for a CS role before.”

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AT&T·Software Engineer·Onsite - Multi Round

Apr 2026
Six months, 564 applications, and 18 interviews later, a senior backend dev in the Toronto area finally landed a hybrid offer in April 2026. The search was a grind with a lot of surprises, and not the good kind.
  • Walk me through how you designed and built a specific service or system at a previous job.
  • You're given an existing codebase. Find the bug in it, and then make a requested modification.
  • Solve a coding problem in the style of a competitive programming challenge (algorithmic, data structures focused).

“This came up constantly across multiple companies, basically a deep dive into something real I'd built.”

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AT&T·Software Engineer·Onsite - System Design / Architecture

Apr 2026
System design round for a software engineer role, just one question about building an emergency notification system. Not a lot of context given upfront so I had to do a lot of scoping myself.
  • Design a disaster and emergency notification system.

“Spent the first few minutes just trying to nail down requirements because this thing could go a hundred directions.”

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AT&T·Software Engineer·Onsite - System Design / Architecture

Apr 2026
System design round with a principal engineer for a software engineer role. Felt like a decent environment to work in, though I left unsure whether they thought I was the right fit.
  • Design a system that records meetings and analyzes customer data from those recordings.

“Big open-ended prompt.”

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AT&T·Software Engineer·Hiring Manager Screen

Apr 2026
One-on-one with a hiring manager that was supposed to be mostly behavioral but surprise, there was a live coding problem. Solved it fine but barely said a word while doing it, and got rejected two days later.
  • Solve a coding problem live during the interview session.

“I actually got through most of it.”

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AT&T·Software Engineer·Onsite - Behavioral / Leadership

May 2026
Got rejected after a behavioral round and the feedback stung a bit because the interviewer actually liked parts of my answers, just not how I communicated them. The core issue was going too deep into implementation details instead of showing I could zoom out and talk about collaboration and decision-making at a higher level.
  • Tell me about a time you influenced peers or navigated a technical disagreement.
  • Can you give an example of communicating a technical topic to different audiences?
  • Describe a situation where you drove improvements to an engineering process.

“This is probably where I tanked it.”

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AT&T·Software Engineer·Onsite - System Design / Architecture

May 2026
System design round for a software engineer role, one question the whole time. Pretty focused session, no fluff.
  • Design a system that assigns server numbers to incoming server requests, supports efficient allocation and deallocation, and maintains separate number pools per server type.

“My first instinct was a simple incrementing counter and i ran with it for a bit before they nudged me toward deallocation.”

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AT&T·Software Engineer·Onsite - System Design / Architecture

May 2026
System design round for a software engineer role, focused on a counting or rate-limiting type problem. The clarification phase was rough because some interviewers seemed visibly impatient, which threw me off more than the actual question did.
  • Design a system for counting, rate limiting, or tracking statistics at scale.

“The question itself wasn't crazy hard but the vibe in the room made it harder than it needed to be.”

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AT&T·Data Scientist·Technical Phone Screen

May 2026
Technical screen for a Data Scientist role that somehow went deep into low-level integer arithmetic. Wasn't expecting to be asked to reimplement multiplication from scratch, let alone handle overflow saturation without 64-bit types. Weird round but genuinely interesting.
  • Implement a multiply function for two integers without using the * or / operators. Must handle negatives, zero, INT_MIN * -1, and run in O(log n) time using a shift-and-add approach.
  • After implementing the basic version, add overflow detection and saturate to INT_MAX or INT_MIN instead of wrapping, without using any 64-bit integer types.
  • Walk through the time and space complexity of your implementation and argue why it's correct for all combinations of positive, negative, and zero inputs.
  • What unit tests would you write to validate this function? Think about edge cases specifically.
  • How would you extend this approach to big integer multiplication, and how does it compare to Karatsuba's algorithm?
  • What changes in your implementation if the platform doesn't guarantee arithmetic right shift behavior?

“I started with naive repeated addition and they immediately asked me what the complexity was.”

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