Cisco Cucm Virtualization Requirements May 2026

Example: If the OVA defines 16 GB RAM, reserve all 16 GB.

When in doubt:

Cisco maintains one of the most strict—and arguably most misunderstood—virtualization requirement documents in the industry. Ignoring it almost guarantees TAC will hang up on you (politely, but firmly). cisco cucm virtualization requirements

Don’t be that engineer. ✅ Hardware listed on UCS compatibility matrix ✅ ESXi build exactly as per Cisco doc ✅ 1 vCPU per physical core – no overcommit ✅ Memory reservation = full VM memory ✅ Thick eager zeroed disks on low-latency storage ✅ NTP configured inside CUCM OS (not host sync) ✅ DRS set to partially automated or disabled for CUCM VMs Need to Check Your Current Environment? Run this from the CUCM CLI:

If you’ve ever deployed Cisco Unified Communications Manager (CUCM) in production, you already know: this is not a “throw it on any VMware cluster” situation. Example: If the OVA defines 16 GB RAM, reserve all 16 GB

Let’s break down exactly what you need to know. Cisco publishes a Unified Communications Virtualization Compatibility Matrix (updated quarterly). If your hardware, hypervisor, or CPU isn’t listed there for your specific CUCM version— it is not supported.

show status show hardware show version active Then cross-reference with the (you’ll need a Cisco.com login). The Bottom Line CUCM in a VM is incredibly stable—if you follow the rules. Cisco’s requirements aren’t bloated; they exist because UC is real-time, intolerant of jitter, and demands deterministic resources. Don’t be that engineer

Have a war story about a CUCM virtualization requirement you missed? Share it in the comments below. This post reflects best practices based on CUCM 12.x/14.x. Always check the latest Cisco documentation before deployment.