Voltage here is standard 230-240 volts. Yet there are three different plug socket types (UK square 3-pin, old UK round 3-pin and German round 2-pin). It is best to buy an adapter that fits all three sockets.
As both local and international call charges are very low in Sri Lanka (data charges are very cheap too) it is a good idea to get a Sri Lankan SIM Card, which you can put in any unlocked mobile phone or Wi-Fi-dongle. Feel free to ask the driver to help you get competitive rates for the SIM Card and Phone Plan. We recommend getting a SIM from DIALOG, which has excellent connectivity.
Local Calls within Sri Lanka: 1 RS/min.
Calling Abroad: 27 Rest/min.
SMS to Sri Lanka: 0.31 Rest/sms
SMS abroad: 6.10 Rs/sms
You can buy a Data SIM for any unlocked Wi-Fi-Dongle. A dongle costs around 3500RS, and you then purchase as many GBs as you require (pre-paid data charges are ca. 100Rs/100MB).
Dongles and Data packages can be purchased at the airport as well. Do not hesitate to ask your driver for help.