From the January 2002 issue of Entrepreneur

Mobile communications took on new significance on September 11, 2001. Mobile phones loomed large in the drama, but many New York wireless networks were damaged in the World Trade Center collapse-or overloaded in its aftermath.

In contrast, the satellite-based transmitters for Iridium and Globalstar satellite phones remained above the fray. Likewise, Research in Motion's BlackBerries kept transferring instant e-mail. That was because the networks they use escaped damage; also, their packet data channels handle traffic increases better than voice channels.

While those companies report a surge of interest, their products are neither invulnerable nor suitable for everyone. Packet data networks are still land-based. BlackBerries use server-based e-mail systems, not the consumer-oriented services used by many companies. Satellite phones are larger and costlier than cell phones.

Still, wireless communications will be important in future emergencies, as their use following September 11 bears out.

Mike Hogan is Entrepreneur's technology editor. Write him at mhogan@entrepreneur.com.