I had an onsite interview, very friendly team. questions were fair, they wanted to know how approach an issue and on what level your troubleshooting skills are. They didn't prove lunch for the interview. Very strong team,

After my recruiter vetted me, there was a phone screen by an Engineering Manager which included general C language programming questions, followed by in person interview with a project lead engineer and HR. The topic of extensive onsite travel for both installations and support is brought up and being unwilling to travel is clearly a deal breaker. They were looking for personality types that were open, friendly and team players and the fact that I was able to hold my end of the conversation helped me - I ended up working under the manager that interviewed me and also have done several projects with the lead engineer that interviewed me. They want outgoing people who can interact and build bridges in face to face contact with the customers, so you must be able to demonstrate that soft skillset!