You will have to install the SQL Server 2000 SP4 or SQL Server 2005 SP2 w/ the OCS 2007 Enteprise Edition. The OCS 2007 SE installs with SQL Server 2005 locally on the Server 2003 server. So no matter what you will be using SQL Server with OCS 2007. OCS 2007 Archiving and CDR is optional and you don not have to install it with your OCS 2007 infrastructure. If you were to use OC 2007. If you were to enable Enterprise Voice on your User accounts then you wouls add a Phone URI entry that would be added to the OCS 2007 RTC database, ResourcePhone table. If you kept your Communication User accounts set to the default of PC to PC you would not write this msRTCSIP-Line value of the User account to the SQL server RTC database, ResourcePhone tableRTC database, ResourcePhone table.