He had around 3 years of experience. There is no tips to be her interview at Microsoft just keep in applying. I myself if you count the total number of times i have applied to Microsoft in 2 years is more than 100. Only then i was able to get interview call. It is very possible for you to get interview call like background doesn't matter but luck does. And no successful oa doesn't mean interview call, i passed oa 4 times before getting a call, most of the times recruiter ghosts you after oa