The first interview is a primary screening by the hiring manager to just go over the things you say you know and at that point he/she invites you for a panel interview. Second interview was a bit more serious because now you're talking to 5 or more people (7 for mine) and the questions come from every angle. They'll ask scenarios and mostly about the devices you've worked on and how you'd configure the device in a certain scenario. Make no mistake about it, these guys know what they are talking about and if you truly know your stuff, you will get the job.

I was first called for the one to one round for technical skills and later a confernce call was arranged from client along with the pannel . It took about an hour and they focus on technical and customer handling skills. Altough my interview was good and kept the decision pending for next day. Next day I got the call from HR and after little negotiation I got the offer letter. I got 2 months notice period and rest was smooth.