My 8220 says SIM card error and goes to SOS signal after a few minutes or seconds of use.
This by its nature is a software issue. There must be a flaw in the OS of the 8220. That is why a replacement corrects it short term until the flaw surfaces. A hard reset by pulling the battery corrects it temporarily in much the same way that rebooting your computer will allow it to work temporarily with a corruption problem.
The OS corruption could be caused by a number of things but I supect that it is probably originating in service books written for a specific carrier. The root files of all of the service books should be audited line by line. As one who has made software and its creation a lifelong hobby I would recommend that RIM re-write the service books for the specific carrier experiencing the issue. This is the only way that the problem can be corrected unless a push method can be developed that can correct corruption in software. This is highly unlikely as flashing a BB device is not like doing the same to a motorola device which is much more simple in its design.
I know that this issue is reported on a very wide scale throughout the US and Canada as that is where the bulk of sales originate for the 8220 device. I predict that a laterversion of the OS will soon be available for download and you will then be able to utilize your Desktop Manager Software and its Application Loader to repair the issue from home.