Vlingo requires a data plan. If you are experiencing connection timeouts or other difficulties with your network connection, open your browser and make sure it can load Web pages with reasonable performance. If it times out while loading pages or if pages load slowly, Vlingo is likely to experience connection problems or timeouts. If the browser cannot connect to the Internet, then neither can Vlingo.
Vlingo works best with a strong network signal. Click BlackBerry Options -> Status [for OS 5 devices] and BlackBerry Options -> Device -> Device and Status Information -> Signal [for OS 6 & 7 devices]. Ideally you want to see Signal somewhere between 0 and -100 dBm. The closer to 0, the better (though you will probably never see much it lower than -80 or so; this would indicate a very strong signal). A value beyond -100 dBm indicates a weak signal and you may experience timeouts. Move to an area where you have a better signal.