I was using T-Mobile with roaming on the China Mobile network and data worked fine. I have now switched to a China Mobile account and, while the display shows "edge", I have a "data connection refused" message on the display and the browser, etc. no longer work. I know that China Mobile does not support Blackberry Internet Email, but the data connection should work. The local people have not been able to provide a solution. Can anyone point me to a possible cause? (The phone is unlocked, of course)

Since China Mobile doesn't support Blackberry, you don't have a Blackberry Data Plan with China Mobile. The only option is to use TCP. You'll need APN settings for China Mobile. If you can get that you may be able to use Opera Mini for internet. But no push email, or BBBrowser, etc.

If you have a Blackberry data plan with anothe provider like TMo then when you roam you don't need the roaming carrier to have blackberry data plans. Does that make sense? What you are seeing is normal.

I understand. I have the APN network ID, but I must need a user ID and password. I'll go back to China Mobile.