Also, the phone has a sticker that instructs users to dial 911 in an emergency. I find it hard to believe that a PBX on a ship would be programmed to dial 911 for emergency, that's a PSTN thing not normally used on internal systems.
You might say they did it on the PBX so that people used to dialing 911 to get emergency services would know what to dial without thinking about it. However, 911 is not the emergency number for the entire world, it's different in many countries. A cruise ship gets passengers from all over the world, not just the US, so it would be stupid to program the phones on the ship to dial 911 for that reason.