When I made a trip to Berlin with AirBnb I found a very old Communication Device in my room. And was on for a surprise... Get a Big Bonus for YOUR TRIP @ www.feierabendbrigade.de/getit.html
Visiting the Island without a guide is much more fun. Use the train with cheap tickets and Rickshaws for the REAL local price with the www.pickme.lk App.
You will need a Sri Lankan SIM card, but you can get one at ARRIVAL before paaport control for 9 US$ with a few GB data and free minutes of calls to foreign countries and domestic calls too.