I got a missed call this morning, and because it had a country code I was unfamiliar with (+92), I went online to check it out. As I suspected, it turned out to be a call that should not be returned. +92 is Pakistan and there have apparently been many scam calls from there. If you return the call, you will end up with a high bill and very likely a trojan on your phone than can access all your private info or capture your login information—or maybe someone trying to con you into sending money for something. Yikes!
So just be warned. This seems to be something that is happening more often here in India.