I maintain a Digicel prepay account year-round. When you're in Jamaica purchase the prepaid SIM and minutes. I purchase the international bundle with my minutes for calls back to the US during my trip and use the rest of my minutes for local calls. When I return home I add small amount of minutes about every 2 months using online top up. You must add minutes every 90 days to keep the SIM active. If the SIM is not used for 90 days the SIM will be deactivated and you will need to purchase a new SIM\minutes. You should be able to "rollover" the minutes until you're on the island again. I typically use some minutes to make calls and or txts back to Jamaica. If I need to call I will sometimes purchase the the "roam like your home" bundle.
Digical has roaming agreements with every Canadian provider per their website. Data is only available through Bell and Rogers. For rates etc see:
http://www.digiceljamaica.com > Coverage and Roaming > Roaming Rates.
The tricky part is remembering to add minutes. If you do that you can use the same number\phone year after year. This is very convenient for obvious reasons. I suggest maintaining a competently separate phone so you can keep Jamaican contacts separate from your "home contacts". Since contacts can be saved to the SIM you could inadvertently end up with both set of contacts on your phone if you're not sure what your doing. Even if it does happen you can remove the unwanted contacts if needed.
Also, I suggest you turn your phone off when traveling to\from the island. This ensures you don't get locked onto a tower which can prevent the SIM from registering on the next network once you land. If that happens you may need to contact digicel to have your phone "logged off" from the tower it's locked to. This doesn't always happen but shutting down should prevent it from occurring.
