Core Issue
When Cisco Unity records messages properly, but Exchange 2000 or Exchange 2003 fails to deliver the messages, the Cisco Unity server may have dual Network Interface Cards (NICs) with each NIC configured for different network segments. This problem occurs only on Exchange 2000 or Exchange 2003 systems, and does not occur with Exchange 5.5.
Resolution
When dual NICs are installed on a Cisco Unity server, both NICs must be connected to the same network segment in order for Exchange to deliver messages.
To confirm or change NIC configuration settings, perform the procedure in the Configuring Dual NICs section of the Cisco Unity Hardware documentation.
Also refer to Cisco Unity Troubleshooting Guide
