Yes, if your service provider has a roaming arrangement with Telecom Cook Islands (TCI), or your phone is not locked to a provider, and your phone will work on a GSM 900 or 1700 network. In other words, probably not. Pay as you go phones will not work either, but you can rent a local mobile from the Rarotonga Telecom office. You should also know that Mama Ru’s provides free local calling, so you can arrange tours and transportation right from your room.