Unified Communications Manager Archives and Deferrals

Archive - Archive releases are considered outdated and have since been replaced by a more recent release.
Deferral - Software that is no longer available due to specific issues/defects - Must only be used after complete understanding of the documented issues. A release is deferred if it has been found to have significant problems or failures in the common use of the product, or presents a security issue. When these quality issues occur or when network availability decreases in the field, access to the images will be restricted. This restriction is called a Deferral. The purpose of this Deferral is to limit customer exposure to these issues and to deliver a fix to existing customers in the field.

Cisco CallManager 3.X Archive
Cisco CallManager 4.X Archive
Cisco Unified Communications Manager 5.X Archive
Cisco Unified Communications Manager 6.X Archive
Deferrals