Using a WP7 phone. I get a signal indication, can use the phone for making calls and texting but cannot use it for any type of data transfer (internet access). I do have a data plan, and I have checked my settings which are ok.
Sorry to hear that Paul, it's hard to troubleshoot what might be wrong especially since you confirmed your settings are okay... could you please post your current settings just to confirm they are all there? :)
(don't take this personally, lol! we all trust you but sometimes a little thing can be overlooked)