Cellular modems have come a long way in the past few years, and since they are now capable of speeds between 400Kbps and 2Mbps, you'll see these services being marketed as mobile broadband. These new data services work wherever you can get a cell phone signal. There are several ways to use mobile broadband to connect your Linux laptop to the internet wherever you go. Several different data services are available, here are the options, providers, and how they work in Linux.

First, some terms: RTT is an earlier cell phone data protocol with speeds up to 100Kbps (2-3x modem speed). EVDO (technically 1x EV-DO) stands for EVolution Data Optimized, and operates on CDMA networks. Built on top of RTT, it operates at 400-700 Kbps typical, 2.5 Mbps max. Cellular providers are quickly rolling out EVDO to all their cell towers, but if you are in an area without EVDO, you can count on automatic fallback to the slower RTT speeds anywhere your phone works. HSDPA is a different data protocol, mainly used by Cingular's EDGE network, and by AT&T. HSDPA modems also work fine in Linux. WWAN stands for Wireless Wide Area Network, and is a blanket term for all high speed cellular data modem technologies.

In Linux, these devices are configured as standard serial ports via the usbserial kernel module. This happens automatically at boot on our systems. You can dial in using pppd, wvdial, or minicom, all of which are detailed in the EmperorLinux manual. The two ways these EVDO modems are physically packaged is PCMCIA (CardBus) cards (for systems without EVDO built-in), and as Mini-PCIe cards (about the size of a postage stamp) that are being built into the next generation of laptops. If you order a Toucan T61, Rhino D830, Koala D430, Raven X61, or Tarantula CF-30, you'll have the option of an internal, Linux-supported EVDO or HSDPA mobile broadband miniPCIe card.

You should first compare coverage areas for the different data providers, to see what EVDO coverage looks like in your area. You'll find full coverage in any large metro area, and many interstates and airports.

Verizon EVDO coverage:
   Zip Code: https://www.verizonwireless.com/b2c/CoverageLocatorController?requesttype=newsearch
Sprint EVDO coverage:
   Cities: http://www.sprint.com/business/products/products/evdoEnterZip.jsp
   Airports: http://www.sprint.com/business/products/products/popup/popupAirports.jsp
AT&T HSDPA coverage:
   Map: http://www.wireless.att.com/coverageviewer/

More information on EVDO is available from Wikipedia.