If you have acquired SBS 2008 CALs from the Volume Licensing (VL) channel, you will be given SBS 2003 CAL keys at the time of acquisition; these keys can then be used for downgrade SBS 2008 CALs to SBS 2003 (R2).

For those of you who have acquired SBS 2011 CALs from channels other than VL, such as FPP and OEM, please use the following product key to activate your SBS 2003 CALs: KJQBH-XJ6YQ-THYJY-PVDCP-87QT6