LED road signs with Internet connectivity

We are going to be implementing an SMS parkingpayments solution in several cities in Greece. The municipality wantsto put several LED display signs on key points throughout the city,which will be showing information about the number of available parkingspaces in this zone. The signs should be large enough to be visible intraffic, though they will mostly be deployed on downtown streets, noton highways. The signs should also be able to connect to the SMSparking server, over the Internet (GPRS? EDGE? 3G?) to download theinformation that should be displayed.