If you hadn't noticed from all the advertisements on TV, the age of 4G wireless is here.

Verizon Wireless will be the latest company to launch its shiny, new 4G network. Starting Sunday, roughly 110 million people in 38 cities will have the opportunity to subscribe to this new generation of wireless service from the nation's largest cell phone operator.

But Verizon isn't the only wireless carrier with a next-generation wireless network. T-Mobile USA and Sprint Nextel also have new networks they are aggressively marketing. And AT&T, which has upgraded 80 percent of its network with the latest 3G wireless technology, continues to claim it has the fastest 3G wireless network in the land.

With all these marketing claims flying around, it's difficult to know which service is right for you. Some consumers are more price sensitive than others, while others simply want the fastest network with the most coverage that's available. For a quick view of what each of the four major wireless operators is offering, check out this chart. CNET has also put together this FAQ to answer some questions that will help you choose a service that's right for you.

Which U.S. operators offer 4G service and which don't Before we get too far into discussing and comparing these supposed 4G networks, let's first establish that none of the wireless operators in the U.S. claiming to have a 4G network actually has a 4G, according to the official standards body, the International Telecommunications Union. The ITU considers 4G technologies to be wireless technologies that offer theoretical download speeds of 100Mbps, and it requires the technology be based on something called OFDM, or orthogonal frequency-division multiplexing.

LTE and WiMax, the technologies that Verizon Wireless and Sprint Nextel (via Clearwire) are using are based on OFDM, but today's versions do not meet the 100Mbps download requirement. HSPA+, the technology AT&T and T-Mobile USA are using, are not OFDM-based and they also do not satisfy the 100Mbps download requirement.

Does it really matter what the standards body says If you are a wireless technology purist, then I'm sure it matters a great deal to you. But for the average consumer, it shouldn't matter that much. But the 4G moniker does make it more confusing for consumers looking to debunk the marketing claims. Traditionally, most people in the industry for the past few years have referred to current versions of WiMax and LTE as 4G. HSPA+, which is the technology AT&T and T-Mobile are using, is a 3G technology. There is no one who disputes that. But T-Mobile likes to say it offers 4G speeds. And now it's just calling its 3G network that uses advanced 3G standards a 4G network.

Regardless of what you call it, it is a leap forward in terms of network speeds. And like LTE and WiMax, HSPA+ offers a noticeable difference in terms of network speeds to consumers. Certain carriers (T-Mobile) claim it's as fast as "4G" technologies. But actual speeds can vary for consumers, so it may depend on where you plan to use the service to determine whether it matches or exceeds other supposed "4G" services.

If speed is the name of the game, which next-generation network is the fastest Based on claims published in press releases and on their Web sites from individual carriers, it appears that Verizon Wireless has the fastest 4G network. Verizon is using LTE for its network. And it claims that it is getting average download speeds between 5Mbps and 12 Mbps. Sprint Nextel with its WiMax network built by Clearwire claims to get between 3Mbps and 6Mbps average download speeds. And T-Mobile USA, which is using HSPA+ technology, says it is getting between 3Mbps and 7Mbps average download speeds.

AT&T, which is also using HSPA+, has not published any claims in terms of speed. But it did cite a report that said the network of the company's nearest 3G wireless competitor runs 20 percent slower than AT&T on average nationally and the largest competitor by subscriber count runs 60 percent slower than AT&T on average nationally. So with that in mind, AT&T's 3G network, on average, is likely offering download speeds between 800Kbps and 1.9Mbps.

How important is network coverage when it comes to "4G" services Coverage is very important. If the service only works in isolated pockets, it won't be useful for people who are mobile. Out of the gate, Verizon Wireless should have pretty good coverage. The initial 38 markets will make the service available to 110 million potential customers. But it won't be able to offer the service to its full 285 million customers for at least three years.

Meanwhile, Sprint Nextel's network is 68 markets, but it reaches only about 103 million people today. And Sprint and Clearwire have been building this network for more than two years. This has been an issue for Sprint and Clearwire in some markets. Even though the company may be in a market and advertising the service to people in a particular city, the service may not blanket the entire city, so certain communities may still be left out. But building new networks takes time and money. Clearwire just said it has raised more cash to build its network through a debt offering.

While Verizon and Sprint/Clearwire build brand new networks, AT&T and T-Mobile are simply upgrading 3G networks they have already built, which in some ways puts them in better positions in terms of coverage with their HSPA+ networks. Since these networks are really upgrades to their existing 3G network, these carriers have simply been able to reconfigure software and tweak hardware to upgrade the network to much faster speeds.

T-Mobile USA, which only just started building its 3G network a few years ago, will be 100 markets by the end of 2010 with HSPA+. And the company says it will be available to more than 200 million potential customers by the end of the year.

AT&T says its HSPA+ network covers 80 percent of its 3G network footprint today, and it expects to reach 250 million potential customers by the end of this year. So in terms of coverage, AT&T will have the widest reach of these upgraded networks.

If "4G" isn't available, can subscribers still get wireless broadband service if they subscribe to one of these services Yes, when the 4G network isn't available, most services will fall back to the 3G network. Sprint is the only carrier out of the four national carriers that offers a service that is only 4G. It also offers a 3G/4G service.

AT&T argues that its fast 3G network is an advantage over Verizon's 4G network. "Verizon said that its LTE speeds will be 10 times faster than 3G. That also means that when you fall back to 3G, you will experience a ten-fold decrease in speeds, which will be jarring. Our 3G speeds are 60 percent faster, on average nationwide, than our largest competitor, which means that when our customers fall back to 3G, the effects will be much less jarring," said AT&T spokesman Mark Siegel.

Of course, AT&T doesn't have an LTE network, so the difference in speed between its 3G network with HSPA+ and the one with an older version of HSPA is not all that different.

Will AT&T get a 4G network too AT&T says it will begin to roll out its LTE network in the middle of 2011. But it won't be an extensive network at first either.

Who offers the best price on next-generation wireless service Currently, all four players have priced their services similarly. Surprisingly, Verizon Wireless is offering the new 4G LTE service for a slight discount. It's about $10 less than its competitors. (It's also $10 less than its existing 3G wireless broadband service for laptops.) I say this is surprising, because Verizon is rarely thought of as a price leader. Verizon also offers a 10GB service for $80 a month.

AT&T and T-Mobile USA are each offering 5GB a month of their HSPA+ service for $60 a month and Sprint Nextel is offering its 3G/4G WiMax service for $60. The 3G service is capped at 5GB, but subscribers can get unlimited 4G service, which makes it a good value.

Because the network speeds are much faster, it's likely that users may blow through their 5GB caps quickly. Verizon charges $10 per 1GB over the 5GB cap and the 10GB. AT&T and Sprint charge 5 cents per 1MB for overages on its 3G wireless services.

T-Mobile now offers a plan where subscribers aren't charged an overage when they reach their 5GB cap. Instead the service slows down if the user has exceeded the 5GB cap.

Is 4G only available as a wireless broadband service for laptops Initially, Verizon will only be offering 4G service for USB data sticks that plug into laptops. Currently, it's only offering one 4G USB modem, which costs $99 with a $50 mail-in rebate. Other data sticks will be announced in the coming weeks, the company has said.

AT&T does not yet offer HSPA+ handsets. But now offers a couple of different data sticks: the USBConnect Adrenaline and USBConnect Shockwave mobile broadband modems. The Adrenaline, which is made by LG, will be the first LTE-upgradeable device. It will cost $50 with a mail-in rebate and a two-year service contract. The Shockwave by Sierra Wireless will work on AT&T's HSPA+ network, and it's free with a two-year service contract and mail-in rebate.

Which carriers offer 4G handsets today Sprint offers two 4G handsets the HTC EVO 4G and Samsung Epic 4G. Both phones have gotten high marks. Sprint also offers mobile hotspots that connect to the 3G/4G networks and offer Wi-Fi connectivity within the hotspot. It also offers a 4G desktop modem. And partner Clearwire is now offering a 4G/Wi-Fi modem for the home.

T-Mobile is selling two HSPA+ handsets, the HTC G2 and the HTC MyTouch.

When will Verizon offer 4G handsets The company hasn't given an exact date, but executives have said they will be showing off LTE handsets at the Consumer Electronics show in early January. Verizon President and COO Lowell McAdam told CNET in an interview in October that LTE handsets will hit store shelves by the end of the first quarter.

Do I have to sign a two year contract Or do any of the carriers offer a prepaid option Right now, Verizon Wireless is not offering a prepaid option for the 4G LTE wireless broadband service. But other wireless operators are.

AT&T offers a pay-as-you-go DataConnect Pass option. Plans for the prepaid service start at $15 for a day pass (100MB data cap) and go up to $50 for a month pass (1GB data cap).

T-Mobile also offers a prepaid service that costs $10 per week for 100MB of data, $30 per month for 300MB, and $50 per month for 1G.

Sprint only offers its 4G service with a two-year contract. But its partner Clearwire has launched a prepaid 4G WiMax service called Rover. The service doesn't require a contract and provides unlimited data usage for just $5 per day, $20 per week, or $50 a month. The Rover Puck, which also creates a Wi-Fi hotspot, will offer download speeds of 3Mbps to 6Mbps. And the device costs $150.