They are mostly called Wireless Broadband. And they work through a cell phone service provider such as Sprint, ATT, Cellular, Verizon...etc.

There are different types:

PCMIA addin cards and ExpressCard slots or USB which is now the most popular as they can be used not only for laptops but for desktops and other devices that have USB ports.

Basically all they are is a single purpose cell phone modem and cannot be used to talk with (A) or call other phones .

A) exceptions....With a program like Skype...a computer can be turned into a phone that will accept calls and allow you to talk through VOIP (voice over internet protocol)

Contact sprint or ATT or other cellular phone service providers in your area for more information....It would be best to have at hand your sons model of laptop to make sure that you are getting the right one!