You can load any 7100/7105 OS (not 7130, however) on to it-doesn't have to be SunCom...try this link for help for the latest OS. Latest Operating System Available For Each Blackberry Device
Download OS Package
Install OS Package to PC
Delete vendor.xml in c:\program files\common files\research in motion\apploader
Run Desktop Manager
Will prompt to upgrade--Give it about 45 mins.....New OS!