Initially a phone call, followed by face to face interview in the Dublin office.
At the time, the company was experiencing rapid growth and was having to scale out systems rapidly - which sounded interesting. They were using big data technologies like Cassandra in multiple data centers.
I was interviewing the company as much as they were interviewing me, and I liked the people and the problems they were working on. I took the job. It took a few months to settle in and I am still enjoying it.