Due to Indonesia requirement to register phone's IMEI number, unregistered phone may not be able to detect a local SIM card.
In such case, after purchasing a local SIM, you can do one of the following:
1. Go to XL telecom store at Sunset Rd (10 mins drive) to register your phone IMEI. The process takes 5 minutes.
2. Rent a mobile WiFi to use the local SIM. It's hassle free (no registration needed)