I think very few people do this anymore.

We have Verizon, which is $10 per day of use, per device, and includes 2gb of data. You can manage the number of days you connect by turning off your cellular. Check in via wifi only, make wifi calls, etc.... But when you need to make a call or get a boatyball, turn on cellular on that device and off you go for $10.

If you travel a lot, and want seamless decent connectivity use, get Tmobile. They have the best global network solution. I would argue ATT has the worst (globally, not in the BVI). I have friends who keep a Tmobile pay as you go phone, and only use it when they travel. They forward their home/other carrier calls. Works great for them. Add a few bucks before each trip.