$19 for unlimited cell phone service? Am I dreaming?

Cash-strapped wireless subscribers can now get unlimited everything smartphone service for less than $20 a month. So what's the catch? And is it really worth it?

That's the question I help answer for one reader in this edition of Ask Maggie. Indeed, Republic Wireless's $19 a month plan requires customers use Wi-Fi wherever they can. While this may be a good fit for some wireless customers, it's not for others.

The same is true of other prepaid services. While the advertisements may make some prepaid services seem cheaper than services from bigger nationwide rivals, consumers need to read the fine print to make sure the service truly offers them savings.

I'll also advise a T-Mobile customer whether he should ditch his contract for a prepaid service from Simple Mobile, a carrier that resells service from T-Mobile.

Ask Maggie is an advice column that answers readers' wireless and broadband questions. The column now appears twice a week on CNET offering readers a double dosage of Ask Maggie's advice. If you have a question, I'd love to hear from you. Please send me an e-mail at maggie dot reardon at cbs dot com. And please put "Ask Maggie" in the subject header. You can also follow me on Facebook on my Ask Maggie page.

Is this $19 unlimited cell phone service for real?

Dear J.,
The Republic Wireless service is very tempting. You are correct that for just $19 a month you can get a wireless service for a Google Android smartphone. This price includes unlimited voice, data, and text. There's no contract, no early termination fees, and no overage charges.

So is it too be good to true? Well, good deals like this are never offered without some kind of catch. For one, this service is so cheap because it's meant to be used in conjunction with Wi-Fi networks. Basically, Republic Wireless hopes that most of your usage will be on a Wi-Fi network, which saves the carrier money.

Since it's impossible to be on Wi-Fi all the time, Republic has contracted with Sprint Nextel to use its network. This means that if there's no Wi-Fi available, you'll simply roll over to Sprint's 3G wireless network. If you live and work somewhere where you get good Sprint coverage, you should be fine in terms of network coverage

But remember that Republic wants you using Wi-Fi more than Sprint's network, so if you use Sprint's network too much, Republic reserves the right to boot you off the service.

How much is too much? It looks like initially users are given about 550 minutes of talk time, 150 text messages, and about 300MB of data usage per month on the 3G network. If you exceed those limits repeatedly, Republic Wireless can cut off your service.

The company clarified its policy on its Facebook page and said that the limits quoted in many stories about its service are just the beginning.

"The more you offload to Wi-Fi, the more you can use," it says on Facebook. "It's truly unlimited. We do have fair use guidelines and we encourage you to use Wi-Fi whenever possible."

Currently, the service only works with one Google Android smartphone, the LG Optimus S. This device will cost you about $200. And the first month of service is included. The LG Optimus S is definitely an entry-level Android smartphone, but it does operate on the Android 2.3 Gingerbread OS.

Now for your real question: Do I think you should ditch Verizon Wireless for this service? First, let me start by saying that service is brand new. The company only began taking orders for the service this week. And it still considers the service to be in beta. So it's still early days, which means that I'd expect there to be some service and customer care kinks to work out. In fact, I saw quite a few people complaining on the company's Facebook page about the order system already going down.

Customer service issues aside, I think the most important thing for you to do is to think about how and when you use your cell phone. For example, if you're on the road constantly and need your phone mostly while driving or some other place that is far from a Wi-Fi hotspot, then this is not the right plan for you.

But if most of your usage is at home, at your office or in other places where you tend to have Wi-Fi access, then this could be a good fit. A number of people have said they think this is a great deal for students or teenagers. Certainly, the $19 a month plan hits the right price point. And students, whether they're in college or in high school, generally find themselves around Wi-Fi a good deal of time.

Still, I have some reservations about relying on Wi-Fi primarily for my cell phone service. For one, it's not always a seamless hand off between the 3G network and Wi-Fi.

The first time you enter a Wi-Fi hotspot with your phone, you'll have to accept the network and type in the password if there is one. Even though your phone will remember this network for the future, it's still a hassle each time you encounter a new Wi-Fi hotspot. Also, even when you're signed into a Wi-Fi hotspot, the transition between Wi-Fi and 3G isn't always smooth, resulting in phone call and data session interruptions.

Also, as much as I love Wi-Fi--and the truth is I really do love Wi-fi--it's just not as reliable as cellular phone service. Devices in my home that are connected wirelessly via my home Wi-Fi router lose connectivity at least once a week. And that's just in my home, where I can reset my router and to some degree control the network. There are lots of other places where you have absolutely no control of the Wi-Fi network.

That said, I think that Wi-Fi will continue to be improved and the technology will evolve. And as a result, I expect it to become a bigger part of most cellular service in the future. Other wireless operators have already been using Wi-Fi as offload for their services. T-Mobile USA also offers a Wi-Fi offload service that allows users to make and accept phone calls over a Wi-Fi network, as well as offload their data traffic.

AT&T, which owns and operates more 29,000 hotspots in the U.S., has even been setting up Wi-Fi hotzones in densely populated urban areas, such as New York City's Times Square and Chicago's Wrigley Field. AT&T smartphone customers are encouraged to use these hotzones and offload their data traffic while in these hotspots.

Of course, AT&T isn't giving customers a break on the price for offloading some of that burdensome data traffic from its 3G wireless network. But since the AT&T data services are capped at 200MB for $15 a month or 2GB for $25 a month, the incentive for using Wi-Fi hotzones is that AT&T won't count the usage against your monthly total.

So in short, I am reluctant to say that you should definitely ditch Verizon for the Revolution Wireless service. Yes, you could save some money. But since this service is still so new, there are a lot of unknowns about Republic Wireless's customer service, as well as, how easily the devices roll over to Wi-Fi and back to 3G as needed. If it were me, I'd wait to hear how others like the service.

That said, I am intrigued by this service. And since you aren't under contract with Verizon anymore, you have more freedom to experiment. The only thing you'd have to lose is the $200 you'd spend on the new phone. If the service is terrible and you hate it, or your usage exceeds Republic Wireless's limits and they kick you off the service, you're only out the $200 cost of the phone.

If you really can't stomach that loss, I bet you could recover some of it by selling your LG Optimus to someone else interested in testing Republic Wireless's new service. If you're up for a gamble, then I'd say give it a shot. Otherwise, I'd wait to hear what other early adopters think.

Is 'Simple Mobile' really a better deal than T-Mobile?

Dear Lucky,
Simple Mobile uses T-Mobile's network, so call quality should be the same as what you're experiencing now with T-Mobile. When it comes to price, you are correct, Simple Mobile's prices are lower than T-Mobile's post paid offering.

Simple Mobile offers two smartphone plans. One plan offers unlimited voice, text and 3G and 4G data for $60 a month, and another service offers unlimited voice, text and 3G data for $40 a month.

T-Mobile's doesn't charge extra for access to its so-called 4G network, which uses HSPA+ technology. And it also offers two "unlimited" plans. The first one costs $90 and it offers unlimited voice, text messaging, and up to 5GB of data per month. The other plan is $80 and it offers unlimited voice, text messaging, and up to 2GB of data per month. T-Mobile calls its services unlimited, but when it comes to data the service isn't really unlimited. T-Mobile doesn't charge extra for more data usage, but it slows service after users exceed their caps.

Meanwhile, Simple Mobile also claims its data service is unlimited. And it doesn't explicitly say anywhere on its Website that it limits data usage. But in the terms and conditions it notes:

To provide a good experience for the majority of our customers and minimize capacity issues and degradation in network performance we may take measures including temporarily reducing data throughput for a subset of customers who use a disproportionate amount of bandwidth. Additionally, in the event that a customer is in violation of the Permissible and Prohibited Data Uses listed above, we may reduce your data speed for the remainder of that billing cycle or terminate data service without notice or refund. We may also suspend, terminate, or restrict your data session, Plan, or service if you use your Data Plan in a manner that interferes with other customers' service, our ability to allocate network capacity among customers, or that otherwise may degrade service quality for other customers.

In other words, when your usage reaches a particular limit, the company can either slow down service or cut service off entirely. Simple Mobile doesn't state what that threshold is, but several customers have said that it's around 1GB of usage per month.

So the question for you is whether or not this service is worth it compared to what you are already getting with T-Mobile.

The first thing to consider is the early termination fee. T-Mobile's early termination fee for customers with more than 180 days left on their contracts is $200. If you have between 91 and 180 days remaining on your contract then the fee is $100. And for subscribers cancelling service with 31 to 91 days left on their contracts, then the fee is $50.

So depending on how much time is left in your contract, it might not really be worth it for you to cancel your service.

You should be able to continue to use your existing T-Mobile phone on the Simple Mobile network. But if you need a new phone, you won't be getting a subsidized handset since you won't be entering into a contract. Right now, T-Mobile is offering several Android smartphones for free with a two-year service contract.

Also if you are a heavy data user, then the T-Mobile "unlimited" plans will likely give you more data to use before your service is slowed down or interrupted. Remember that T-Mobile's limits are 2GB and 5GB, whereas it appears that Simple Mobile's limit is around 1GB a month.

At any rate, it's important to read the fine print and think about all the fees and variables before jumping ship for a prepaid carrier. Even though some of these services may look like a good deal, when you dig below the surface and look at what you will actually get for the service, it may not be worth it.