I recently learned about this 4 digit pin number procedure when I called Carnival to change a cruise booking date and was asked for my booking number as well as four digit PIN number by the representative. The representative was unable to speak with me at first because I did not know the PIN number, but after figuring it out I called back and was able to get help.
Lessons I Learned From This:
1. When you initially book your cruise you may or may not have to create a PIN number for the booking. However, if you do make sure you remember the number. If other people on your booking will need to conduct any business with Carnival you may want to share the booking's PIN number with them.If you do not wish for the others to have your PIN number, just don't share the information with them!
2. If you get a call from Carnival about possibly upgrading staterooms the phone representative will likely ask you to setup a PIN number for the booking then, if you do not already have one.
3. Carnival's website has no information regarding the PIN number procedure, but the phone customer service representatives are very into making sure a correct PIN number can be provided. If you call Carnival's phone number and after selecting the option to speak with someone about an already booked cruise, you will hear the waiting system remind guests to have their booking number and PIN number ready. This means the PIN number process must be fairly common for it to be in the phone recording system.
4. In theory, if a PIN number is created for a booking, only the person or people that can provide the correct PIN number should be able to make changes to the booking. However, I am not sure what happens if someone truly forgets their PIN number or if there are any cases where the PIN number system was circumvented accidentally. If you know of anything about either of these two possibilities please feel free to share because I am curious to know of any cases.
5. I do not know for sure if this would be applicable to bookings with travel agents.
There may be other parts of this system that I am unaware of, but I hope hearing my experience will make everyone a little more aware. I should also mention Carnival's customer service representatives were fantastic and did a great job assisting me. Although the first agent could not speak with me about the booking, she was extremely nice. The second agent quickly helped me once I provided the booking and PIN numbers and within minutes had my cruise dates changed!
Although I have been cruising for over a decade, I am always learning something new and finding out about different procedures. Keep records of all your booking documents and if you have a PIN number make sure you remember it!