That would be Farsi. But I'm not aware of any large numbers of support staff that have been outsourced to Iran or the Middle East. A lot of the more conservative segments of the Persian and Arabic populations still don't take too kindly to capitalist American influence
Most of it is India, and even then, knowing how to speak Hindi probably won't help. A lot of people in India technically speak the same language, but don't understand each other because the dialects have shifted so much. So the common language between them all is English (good old fashioned colonial influence). You still have to put some effort into understanding the accent, but I've found that thinking of the speech as someone trying to talk with their tongue outside of the mouth helps.
