If your organization has a policy that requires the content of every communication to be logged for compliance purposes, you should deploy the Archiving and CDR (call detail records) Server. If you need to track only call detail records (for example, when a conversation occurred between users without archiving the conversation itself), you also should deploy the Archiving and CDR Server. This server role enables archiving of all messages at the server level. You can enable only archiving or only call detail records (if you don't want to archive the actual body of the IM conversation, but you do want to collect statistical usage data). Because all IM conversations travel through the user's home server, it is possible to enforce archiving at the server level without requiring any cooperation from the client. This architecture offers the most control to the administrator.

The Archiving and CDR Server must be installed on a Windows Server 2003 or Windows Server 2003 R2 computer with SQL Server 2000 SP3a (or higher) or SQL Server 2005 SP1 (or higher) installed. The Archiving and CDR Server cannot be collocated on the same physical server with any other Office Communications Server role. See Table 2-4 for the hardware and software requirements for this role.