How much should I be paying for prepaid minutes, and what kinds of plans are available?
Most prepaid carriers charge anything from 10 to 60 cents a minute, depending on the plan--and there are a bewildering number of variations to consider. The bottom line is that there's no one prepaid carrier with an exceptionally good or bad deal, just a dizzying array of variations that may or may not make sense depending on how you use your phone. Read the fine print and consider the big picture before making your choice.

For plans in which you buy buckets of minutes ahead of time, an important factor is the number you buy at once. If you want a relatively small bucket of minutes--say, 150 or so--you'll probably pay 30 cents a minute or more. The more minutes you buy in a chunk, the less you'll pay per minute--down to about 10 cents per minute if you buy 1,000 minutes or more. If you're a frequent chatter, it's probably worth it to cough up the dough for a big bucket of minutes. Also think about when you call, because just as with a traditional plan, prepaid nights and weekends can be cheaper than weekday peak times.

With some prepaid accounts, daily access fees also apply. This could be up to $1 for each day you use your phone or for every day, whether or not you place a call. The every-day access-fee plans usually offer lower per-minute rates, which might be a good deal for heavy-duty talkers; light chatters will probably be better off spending a bit more per minute but paying access fees only when they use their phones. And for those who rarely use their phones, paying even more per minute but avoiding the access-fee plans altogether is probably the best idea. Carriers with monthly autopay options usually give you a better deal on your cost per minute (sometimes close to 10 cents a minute) and typically don't charge daily access fees, but they may gouge you on additional minutes for a given month (often 45 cents a minute or more) or charge you a monthly fee. While the autopay option can be a good deal--especially if you use a lot of minutes per month--make sure your plan includes all the minutes you'll likely need, and keep an eye on your balance.

Confused yet? Here's another wrinkle: in many cases, those minutes you buy don't last forever. Your buckets of minutes and prepaid cash cards will often expire after a set number of days. Not only that, but some carriers make you add a set number of minutes or cash each month to keep your account active, even if you still have minutes or cash remaining on your account. And if you opt for a monthly autopay plan, bear in mind that your monthly allotment of minutes might not roll over.

But wait--there's more. Some prepaid carriers charge high per-minute rates but sweeten the deal with cheap or free night and weekend minutes or unlimited mobile-to-mobile calling--that is, free calls between you and another subscriber using the same carrier. Other costs to watch for include fees for roaming, long-distance calls (particularly for international dialing), text and multimedia messages, and downloads for games and ring tones.

Who offers prepaid plans? And what's all this about MVNOs?
Of the major U.S. carriers, AT&T, T-Mobile, and Verizon now offer prepaid plans. Meanwhile, other companies without the network infrastructure of the big four carriers are getting in on the act. These MVNOs (mobile virtual network operators)--including Virgin Mobile, Boost Mobile, TracFone, and Liberty Wireless--buy huge batches of minutes from the traditional wireless carriers, essentially piggybacking on those networks to offer their own brands of pay-as-you-go wireless service. While MVNOs didn't used to have the extra services that the big carriers did, such as text messaging, ring-tone and gaming downloads, and Web browsing, that's beginning to change.