Your mobile phone will probably not work - if you can't live without one, then you can hire one at Rangoon airport or you can buy a local sim card which are freely available. The cost is approximately $2 per day with $50 deposit. At the airport there is the Yatanapon rental service. You do not need to order in advance. You will be able to use a computer at your hotel if it has wifi – check before booking.
We will provide a basic Burmese mobile phone with some pre paid cards. It will have telephone numbers in its memory that will be useful for you.