The asian students that I used to have all recommended that I learn Urdu (not that I took their advice!) The topic came up when I remarked that, when they were talking together they would occasionally lapse into a few words of English, before returning to their "own" language. They explained that Urdu was used as a lingua franca by them, as they mostly came from different parts of the sub-continent and had different mother-tongues. They used English now and again if there wasn't a handy translation for an English noun.
But they reckoned that I could learn enough Urdu to be useful within three months.