Notebooks and Cell Phone Connection

My boss has a need to access lots of data when on the road, plus his calendar, etc. He presently uses a cell phone (don’t know brand) and was told he needs a booster for a better and more reliable connection. HOwever, I[‘d like to know what is theBEST way to connect to your data while on the road via a notebook computer (which he prefers as he doesn’t like PDAs – he’s a fast typist). It’s been a few years since I became acquainted with this technology so I badly need an update. Thanks.