I don't know about the lingua franca thing, but it is the mother tongue of Ismail Noormohamed Abdul Rehman (aka Merchant), born in Bombay, so it has a long reach. Apparently, the preservation of Urdu culture and literature is an abiding passion of Mr Rehman, and he even made an entire film devoted to the subject (if it were an autobiography he might have called it "Rehmans of Bombay"). It seems somehow unlikely to me that an "Esperanto" would develop such a culture, though not impossible.