Just got through T-Mobile's technical screen process for a mid-level SWE role in May 2026. Here's the breakdown since this took me way too long to find before I went in.
For my role (mid-level, Bellevue team), there were two technical coding stages:
Stage 1: HackerRank OA Sent after the initial HR call. 90 minutes, 3 problems. All of mine were standard LeetCode medium difficulty: one string manipulation, one array/two-pointer, one graph BFS. No dynamic programming in my set, but I've seen others report a DP question at the senior level.
Language support is broad. I used JavaScript, which is fine for frontend roles. The OA is not proctored beyond a browser lockdown. Time management matters: 30 min per problem is tight if you don't recognize the pattern fast.
Stage 2: Live Coding Interview This was 45 minutes with one engineer on Google Meet. One problem, medium-hard LeetCode equivalent. Mine was a modified interval merging problem with a twist around overlapping time windows. They care a lot about talking through your approach before writing code. I spent 8 minutes talking through edge cases and the interviewer actively contributed, which I liked.
They explicitly said they don't expect you to finish under pressure, they want to see your thought process. I ran out of time on the optimal solution and got the offer anyway. The interviewer's last question was "what would you do differently if you had more time" which is a good sign they're evaluating your reasoning.
What to prep: LeetCode mediums, especially graphs and intervals. Know your time complexities and be able to explain them. They asked me to walk through a small test case by hand before running it.
Not the hardest coding interview I've done. Definitely below FAANG bar but above what I've seen from regional tech companies. The live coding interviewer was low-pressure and actually helpful.