Originally Posted by mk1151
it means that your carrier does not have your account provisioned for data services (including e-mail). This may be a temporary issue (carrier problems) but I would call them up anyway.
Last option before calling would be to power down your device, remove and re-insert your SIM card, then power it back up...
By the way - this morning I had that message (Providence, RI) and I just turned off the radio and then turned it back on again. It sure is faster than dealing with batteries and SIMs.