Digicel has a store in the plaza near Burger King in Negril. For about $40 US (possibly less) you can get a decent phone, with a sim card and buy credit for phone usage. Considering that Verizon costs ~ $1.59 per min with their International Plan, more if you don't have that on your account, but the cost of using Verizon for just 25 minutes worth of calls would be the same as the cost of buying a phone. Even without International plan, it is cheaper to call US from JA using local phone.

If you have an unlocked Quad Band phone, you could use that & just buy a sim card from your choice of local providers.

PEACE