a418c269__IP_Phone_8900_Series____Cisco_eature_support_during_failover_Notes
[Feature] Voicemail [Supported] Yes [Notes] 
Your voicemail will not be synchronized with other users in the Cisco Unified Communications Manager cluster.
Cisco Unified IP Phones 8941 and 8945 User Guide for Cisco Unified Communications Manager 9.0 (SCCP and SIP) - Calling Features [Cisco Unified IP Phone 8900 Series] - Cisco