Went through Twilio's full loop earlier this year for a senior program manager role. The behavioral portion was two rounds, each 45 minutes, and it was much more structured than I expected from a company that markets itself as developer-first.
They have a set of competencies they're mapping to. Based on my experience the main ones were: customer obsession (with a lowercase c, not Amazon's branding), cross-functional collaboration, navigating ambiguity, and what I'd call "building vs. scaling" stories, where they want to know if you've owned something from zero to one AND from one to ten.
Questions I actually got: Tell me about a time you had to push back on a priority that leadership had already committed to externally. Describe a situation where the technical constraints of a product forced you to rethink the customer promise. Walk me through a project where you had to build alignment across engineering, sales, and customer success simultaneously. Tell me about a time you had incomplete data and had to make a call anyway. What was the outcome and what did you learn?
That last one came up twice in two different rounds from two different interviewers. It felt deliberate.
The interviewers at Twilio pushed for specifics more than most. When I gave a general answer, they'd say "can you be more specific about what YOU did vs. the team?" I had to adjust my prep to build out the individual contribution layer of every story.
One thing I noticed: they really do care about customers in the telecom / developer sense. If you don't have a story about working with developers or API users, try to at least frame your customer stories in terms of technical buyers.
What worked: STAR format, but heavier on the Resolution and the Learning at the end. They like when you can articulate what you'd do differently.
What didn't work initially: I led with a team win and they redirected to my individual role immediately. Keep the "I" prominent.