There is good cell phone coverage in most of the ports in Thailand, but long-distance calls can be expensive. We recommend that before embarking on your cruise, you give our office number to your important contacts. It can also be helpful to purchase a Thai Sim card (about 2 Euro), so that you can make calls within Thailand at a reasonable price.
There is no cell phone coverage in Burma and the Andaman Islands past Kawthaung or Port Blair.