SIM CARD IN BALI
You will want a sim card in Bali! Especially if you are the type who really depends on their phone and google maps. Although you can just download offline google maps on your phone but the issue with this is that it doesn’t always work because of signal and sometimes you really need data. In May 2018, we bought a sim card at the airport when we arrived and it cost 300,000IDR for 15GB of data and 15 minutes of local calling (Update: It seems as though the prices have become cheaper since 2018). There was 3 of us so we only bought 1 sim card and we shared hotspot whenever we wanted (careful though.. This drains the battery on the phone who has the sim card). We didn’t get through all 15GB of data for the 9 days that we were there but it was nice to have at our disposable. It was also convenient to have the 15 minutes of local calling because when we would order a ride using the GRAB app, sometimes the driver would call us to try to find us.
If you have to choose which company to go with, I highly recommend Telekomsel. They have the best signal all over the island.
P.s. depending on where you look, it may be cheaper to buy a sim card somewhere outside of the airport. You can find random sim card stands on the street but all the ones that I saw were actually more expensive than the airport. I think you need to visit an actual store to get the cheaper rate. I personally felt that it was worth it to get the sim card at the airport right away.