A couple of months ago, I wrote a blog post titled “Is Your Cell Phone Contract Becoming Obsolete” about how you can save lots of money each month on your cell phone bill using a prepaid service. Since then, there have been several innovations that have made prepaid carriers even more attractive, especially some of the lesser known ones that you probably haven’t even heard of. If you’re thinking of breaking free from the Big Four contract carriers (Verizon, AT&T, Sprint, and T-Mobile) but aren’t sure which alternative might be best for you, here are some questions to consider:

1)      Which network(s) work best for you? Even the best plan and phone is practically useless if you don’t have service. Each of these prepaid carriers offers access to one or more of the Big Four networks so you’ll want to make sure that the network they use works well wherever you intend to use your phone. In general, Verizon is the largest network, followed by AT&T, Sprint, and then T-Mobile but coverage can vary significantly based on where you actually are.

2)      How important is your choice of phone? The carriers vary widely in their selection of phones available. If there’s a specific phone you want, check to see if the carrier supports it.

3)      How will you use the phone? If you plan to talk a lot on the phone, you need a lot of voice minutes. If you’ll use it more for Internet access, data and a fast network may be more important. Some carriers forbid using your phone as a Wi-Fi hotspot (which allows you to share your phone’s Internet access with one or more computers) while others charge extra for it since it tends to use up a lot of data. One even disallows streaming music and video over the cellular Internet connection for the same reason.

With those questions in mind, these are the 5 carriers that I consider to offer the best value for the budget-conscious smart phone user (other carriers may be better if you don’t need a data plan):

Republic Wireless

Network: Sprint 3G with free roaming on Verizon, America’s largest cell phone network

Plan(s): At $19 a month, Republic offers the lowest price for unlimited talk, texting, and data. (They used to have “unofficial” caps but have recently lifted those.) The reason they can offer such low rates is that Republic uses Wi-Fi for calls rather than a cellular connection whenever it can. The service is in Beta right now so you can only sign up to get in line and wait your turn. Tethering and using your phone as a Wi-Fi hotspot is not allowed.

Phones: You’re limited to using their Wi-Fi calling enabled phone, the Motorola Defy XT, which is a mid-range Android phone that’s designed to withstand dust, water spills, and even the occasional fall.

Ting Mobile

Network: Sprint 3G and 4G on Sprint’s existing WiMAX and upcoming LTE networks with free roaming on Verizon for voice

Plan:  You only pay for the service that you actually use each month so low to mid level users can save a lot of money but heavy users can pay more than with other prepaid plans.

Phones: The choice is limited but in a few weeks, they’re coming out with the Samsung Galaxy SIII phone, a brand new phone that is considered by many to be the best Android phone if not the best smart phone available.

Virgin Mobile

Network: Sprint’s 3G and 4G through WiMAX

Plan: For $30 a month (with a $5 discount for autopay), you get unlimited texting and data but only 300 voice minutes a month. (After that it’s still only 10 cents a minute.) You can also get 1200 minutes and unlimited texting and data for $40 and unlimited everything for $50. Wi-Fi hotspot is another $15 a month.

Phones: The choice of phones is limited but includes the dual-core Evo V 4G Android smartphone and the lowest 2-yr cost for the iPhone 4S.

Straight Talk

Network: Choice of AT&T or T-Mobile with up to 4G speeds on HSPA+

Plan: $45 for unlimited everything but using your phone for tethering, as a Wi-Fi hotspot, or for streaming music or video is prohibited.

Phones: You can use any AT&T or T-Mobile phone or any unlocked phone that uses a SIM card so it has the widest selection of phones, including the previously mentioned Samsung Galaxy SIII and the iPhone 4S.

Boost Mobile

Network: Sprint 3G and 4G through WiMAX

Plans: Unlimited everything for Android phones start at $55 per month but reduce by $5 for every 6 months of on-time payments to $40 per month. There are also a variety of pay-as-you-go plans for people who don’t use their phone much. Wi-Fi hotspot is $10 per month.

Phones: The choice is limited, with the top phone being the mid-level HTC Evo Design 4G Android phone.

I’m currently on Virgin Mobile with a grandfathered plan at $25 a month for unlimited data and 300 minutes a month. (Since I tend to go over my minute limit, my bill usually comes to about $35 a month.) I’ve been pretty happy with the service so I might stick with it and just upgrade my phone but I’m also intrigued by some of these other options. I’ve signed up to be on Republic’s waiting list, which would provide me with a better phone, unlimited everything, and roaming on Verizon’s network, all for a little over half of what I’m paying now. I’m also tempted by the 4G speeds, free Wi-Fi hotspot, and much better smartphones on Ting, which would cost me about $42 a month according to my typical current usage. (Besides, who wouldn’t want a cell phone service called “Ting?”)

What do you think? Do you have any experience with any of these lesser known carriers? If not, would you consider any of them? Leave your thoughts in the comments section below.