Applied online. Recruiter contacted for initial briefing. Phone interview was scheduled. I was given a number to call, I called on time, some conference was going on when I called the number, I was asked to call after 15 min. I called back after 15 min, the conference was still going on, they asked me to stay on line while they wrap up.

Interview started, it seemed they were not interested in interviewing me....very unprofessional. They asked very basic question, interview ended. I was not notified if I was selected or not.

Name some design patterns.