Standard behavioral interview ("Tell me about a time" questions), plus a writing test. The ad was misleading, though, and described duties that were not actually a routine part of the job. It turned out to be a cattle call for people to answer phones in Frontier's call center. On top of that, they told me they didn't actually have any direct employees and that all (!) of their workers were employed by staffing agencies. That was a pretty big red flag for me. Lastly, the pay would have been competitive about 15 years ago, but isn't enough to meet today's cost of living, especially not in an expensive city like Fort Collins. I might have been willing to accept the pay if there had been a possibility of temp-to-hire and some track for advancement, but it was made clear to me that there wasn't.
And now you know how they manage to keep their fares so low.