At look at the leading wireless carriers -- Sprint Nextel, Verizon and Cingular -- which are rolling out 3G networks. The three leading wireless carriers are all in the process of rolling out 3G networks. For Sprint Nextel and Verizon, 3G involves an upgrade from the Code Division Multiple Access 1x (CDMA) network for data to 1x Evolution Data Optimized (EV-DO). For Cingular, which supports GSM technology, it means evolving from enhanced data rates for GSM Evolution (EDGE) to High Speed Download Packet Access (HSDPA).From a company perspective, there are four key questions related to 3G:What does 3G mean for my mobile workforce?Previous generations of wireless data networks were suitable for wireless e-mail and customized products that helped optimize applications for throughput-challenged wireless networks. All that changes with 3G.Throughput rates for 3G average 400K to 700Kbps, which means for the first time the WAN is a viable contender for remote access. With a PC card and a VPN client, mobile workers can access their corporate applications wherever there is cellular coverage. Where 3G is not yet available, the service is backward-compatible to 2.5G (EDGE for Cingular, and 1x for Verizon and Sprint).I have been using a data-only card from Verizon Wireless for about a year. The bottom line: Even though it's not as good as broadband in the office or Wi-Fi, it's good enough most of the time. The data-only service has displaced somewhere between 50% and 75% of my traditional remote broadband connections (such as Wi-Fi hot spots or hotel room service).At $60 per month for unlimited service, the ROI on a $7-to-$12-per-day broadband connection becomes quite evident. There's also the convenience factor of the same sign-on and authentication procedure no matter where you are.Is 3G ideal? By no means. Coverage still varies by operator and location, but will improve markedly in 2006. And the high-throughput rates pertain mainly to the downlink, whereas the speeds are limited to 80K to 140Kbps on the uplink. This means higher-than-desired latencies, and problems in sending or uploading large files.Are there differences between carrier 3G offerings?You will see a lot of marketing in 2006, as each operator touts its version of 3G. Here are the main differences:Coverage. At this early stage, there are substantial differences by operator and by market, so you should evaluate carefully. Verizon has the clear lead, Sprint Nextel is catching up quickly and Cingular has aggressive plans to cover 50% to 75% of its footprint by year-end. By mid-2007, we will be closer to parity, and the greatest differences will be outside major metropolitan areas. Also note that as of now, Cingular's 3G service is only available on PC cards, not phones.Network performance. Promised throughput rates are all in the same range, although HSDPA is newer and less proven. We don't know what happens yet when these networks get truly loaded. Latency is another consideration, with HSDPA having a slight advantage. Finally, voice and data sessions can be run simultaneously on HSDPA but not on EV-DO. This is not an issue with respect to laptop usage, but it could be a differentiator for PDAs and 3G phones, depending on your use case. If you are thinking about using VoIP over 3G, I would not recommend it at this time. The QoS is not adequate for mobile VoIP, and carriers will not support it. Upgrades to the 3G network planned for 2007 will make VoIP possible, if the carriers allow it.At this time, the norm seems to be $60 per month for unlimited use, plus $100 or so for a PC card. After that, there are some subtle differences by operator. All this is negotiable if you're considering more than 25 lines. Some operators offer a discount on PC card access if you have BlackBerry service, or they will allow you to use a 3G-enabled phone or PDA as a modem.Devices. There aren't significant differences among PC cards, but there are among the connection clients that come with the cards, mainly in the areas of ease of use, Wi-Fi capability, and authentication and security features. Also, some of the first 3G-equipped PDAs are just now becoming available. Cingular should launch its first HSDPA-capable handset this quarter.What kinds of decisions must I make?This is a year when operators will be encouraging you to upgrade to 3G. Here are the key questions you should ask:Is the coverage adequate for the patterns of my mobile workers?Am I interested in PC-card remote access or a 3G-equipped PDA?Is this a new implementation, incremental to mobile e-mail, or a replacement? How does it fit with my broader remote access strategy?Do I want a data-only service or device, or something that includes both data and voice?What about Wi-Fi and WiMAX?Wi-Fi hot spots continue to spread, but IT executives know by now that the public 802.11 infrastructure remains a fragmented hodgepodge. Municipal Wi-Fi provides broader coverage but is suitable only for those who travel in a limited area. The current WiMAX standard does not allow for mobility. Corporate offerings are in a very limited number of markets today and are primarily focused on a wireless replacement for a broadband connection at a fixed location. Mobile WiMAX, or 802.16e, is part of the broader discussion about a 4G wireless network that could have an impact later this decade. The WAN is not standing still. We should see upgrades to current 3G networks over the next 12 to 18 months. For example, EV-DO Rev A promises:Faster uplink speeds and a more symmetrical network architecture.Reduced latencies.The possibility for VoIP over the WAN.The bottom line is that the 3G WAN currently offered is the best we're going to have, on a broad geographic basis, for the next three years. However, if the only thing you need is e-mail access from a PDA device, you don't need 3G.