Need to check your e-mail or use the Internet when you're on the go? You can get online using cellular access with compatible phones, handheld PDAs and laptops. Before you sign up, it pays to do your homework. Pricing, speeds and coverage vary greatly.

Verizon Wireless, for example, offers two cellular Internet plans: NationalAccess and BroadbandAccess. Unless you're doing light work, the NationalAccess speeds of 60 to 80 kbps will be unbearable. It's just a tad faster than a dial-up modem. Monthly, it costs $49.99 for PDAs and $59.99 for laptops, in addition to your current plan.

The company's BroadbandAccess claims download speeds of 400 to 700 kbps. It's only available in 53 metropolitan areas. And it's not cheap.

For unlimited use, it's $79.99 monthly for laptops. Handhelds and PDAs cost $49.99 monthly. This is in addition to your regular wireless service bill.

Cingular's Edge offers coverage in more than 13,000 U.S. cities and towns. Its average download speeds range from 70 to 135 kbps. This is better than Verizon's NationalAccess. However, don't try to use your company's intranet or VPN. I did, with full bars, and the delays are quite noticeable.

Plans start at $20 a month for limited usage or 5 MB of data transfer per month. Unlike minutes, data transfer is difficult to judge. An unlimited plan may be a safer bet. Cingular charges $80 per month for unlimited data for laptops and $45 for PDAs. This is in addition to your monthly service plan.

Some newer laptops are ready for cellular access and may include a free 30-day trial, such as the Sony Vaio T-300 Series. If not, you can purchase a PC card that includes an antenna for your laptop. Expect to pay between $100 and $200, although this is often discounted with new service. Similar add-ons are available for handhelds and PDAs.

Alternatively, you may be able to use your cellular phone as the laptop's modem. Check your service provider's Web site for mobile toolkits. These cost around $50 and include the software and, if necessary, a USB cable. Some phones may not need this as they connect via Bluetooth.

For now, 3G is only available from Verizon, Cingular and Sprint. But T-Mobile plans to launch a 3G network.

Existing 3G networks will get faster. Verizon is promising faster speeds. And Cingular plans offer speeds of 400 to 700 kbps by the end of the year in up to 20 markets.

As the service speeds grow, expect new features to appear on cell phones. Manufacturers such as Samsung and LG are already working on integrating VoIP. Voice over Internet protocol, as it's properly called, routes calls over the Internet.

When a wireless hotspot is detected, cellular calls are routed over the Internet. This can cut down on monthly phone bills.