Interview process is nothing different than many other indian companies do.
2 round from india panel and it was like junk questions.
Interview with USA panel was really something interesting and they going to ask you the real thing and if u not know deep knowledge you cannot clear interview.
But i suggest stay away from such companies as they follow total unethical process.
A company cannot contact previous employer without candidate consent and specially they should not talk your ex teammates.
If they want to know something then HR department is channel for this.