SIM card question

[wrtiii]

So the sim card basically just allows my phone to operate?

Yes, and it is what gives your phone a phone number. In Jamaica, that will be an 876 number. There are plenty of videos on how to change your iPhone SIM, just Google it. The person who sells you the SIM will also be able to install it in about 15 seconds.

After that I still need to buy a plan - or minutes? To be clear I just want the ability to make and possibly receive calls, all local.

Yes. Trivially easy, and you can buy a card that will give you more minutes in many places, including pretty much any convenience store. I think JMD100 is the standard, which is enough to make a bunch of calls. The card will have a scratch-off section that will reveal the code number, and you add the time to your phone by dialing then entering the code number. Again, if when you buy the SIM card you buy some minutes, the person selling it will add it to your phone for you.

How do I get my own "phone number"?

SIM card = the phone number.