CUCM Upgradation and Migration takes an ample amount of planning and prerequisites check before actual migration and post-migration. In this article, we will discuss how the approach should be.

Most of the environments are still running on 8.5 which is EOL and EOS (End of Service). To get back to pace, everyone must plan for upgradation to a stable version which is (n-1), where n is the latest version.

For most migrations, you need to plan a hierarchy upgrade to reach 12.5. But here we will discuss where a method is supported which does not involve hierarchy upgrades.

Here is how you should plan

Current CUCM version: 8.5.1

Desired CUCM version: 12.5

Number of Nodes: As per environment

Supported upgrade method:

PCD Migration

Recommended plan: Migration from CUCM using 8.5 to 12.5

Note: Licensing till CUCM 11.5 is done on PLM but CUCM 12.5 will use smart licensing.

Action plan:

  1. Pre-Planning
  2. Perform pre-migration tasks
  3. Perform the migration
  4. Do post-migration tasks


Understand Limitation of CUCM:

The number of Unified Communications Manager subscriber nodes in a cluster cannot exceed 4 subscriber nodes and 4 standby nodes, for a total of 8 subscribers. The total number of servers in a cluster, including the Unified Communications Manager publisher node, TFTP server, and media servers, cannot exceed 21.

DNS Requirement:

If your deployment uses DNS—Unified Communications Manager and IM and Presence should use the same DNS server. If you use different DNS servers between IM and Presence and Unified Communications Manager, it is likely to cause abnormal system behavior.

Server—In the Cisco Unified CM Administration Server Configuration window, set IP addresses for your cluster nodes.

CCMCIP Profiles—In the Cisco Unified CM IM and Presence Administration CCMCIP Profile Configuration window, point any CCMCIP profiles to the IP address of the host.

Power Supply

Ensure that you connect each node to an uninterruptible power supply (UPS) to provide backup power and protect your system. Failure to do so may result in damage to physical media and require a new installation.

Bootable ISO files required:

CUCM 12.5

Pre-Migration Tasks

  • Confirm if the existing hardware is supported for the newer CUCM version.
  • Export user records using BAT.
  • From Cisco Unified CM Administration, choose Bulk Administration > Users > Export Users.
  • Click Find to display all user records
  • Click Next
  • Provide Filename and format.
  • Enter job description
  • Click Run Immediately
  • Click submit
  • To download the exported file, choose Bulk Administration > Upload/Download Files.
  • Locate your filename and click download selected.
  • Ensure you have a minimum of 25 GB of required common free space to upgrade to a newer version.

However, your deployment may require more space if you have a lot of TFTP data (device firmware loads), music-on-hold (MOH) files, or if you have many locale files installed. If you do not have enough space, perform one or more of the following steps to create enough space:

  • Use the Free Common Space COP file (ciscocm.free_common_space_v<latest_version>.cop.sgn). This COP file removes the inactive side in the common partition to increase available disk space without requiring a system rebuild. Ensure that you review the Readme file that supports this COP file before you proceed.
  • Manually remove outdated or unused firmware files from the TFTP directory. You can remove these files using the TFTP File Management page in the OS Administration interface, or you can use the file list tftp and file delete tftp commands from the command line interface.
  • Ensure that you have the necessary license files for the new release.
  • Ensure that there are no expired certificates on the partition, including any trust certificates in the certificate chain.

Perform this step for refresh upgrades on IM and Presence Service nodes only. Expired certificates are not imported during a refresh upgrade. As a result, a new certificate is generated during the upgrade process and can cause errors.

  • Back up your system, ensuring that you use a network device as the storage location for the backup files. 
  • Disable extension mobility before you begin the upgrade process.

From Cisco Unified Serviceability, choose Tools > Service Activation > Stop

  • Make sure you are not using any special characters in the CUCM password.
  • Add a serial port to the virtual machine so that you can dump logs in the event of an upgrade failure. Steps to do it are:-
  • Power off the virtual machine.
  • Edit the settings to add a serial port.
  • Attach the serial port to a .tmp file.
  • Power on the virtual machine and proceed with the upgrade.

Migration Task

  1. Install ESXi (Vmware)



4 GB RAM, 80 GB hard disk

2. Deploy PCD virtual machine (delivered as a virtual appliance)

3. Download OVA and .ISO images for 12.5 CUCM

4. Create target virtual machines using OVA. Similar to nodes of previous call manager.

5. Discover Cluster – PCD connects to source cluster and retrieves cluster information.

It installs a cop file which will run a script to get the output of the following information:

Show network cluster

Show hardware

Show version active

Show version inactive

6. Add ESXi hosts (for the VMs you will use) to the PCD inventory

7. Create Migration Cluster – define the mapping between source nodes and target virtual machines. (Make sure the target VM’s are turned OFF)

* Create Migration Cluster (to Cluster)

Inventory -> Clusters

Click “Add New UC Cluster”

Select “Create a cluster by migrating an existing cluster”

If Simple Migration chooses the “Use the source node network settings for all destination nodes” option when creating the migration cluster.

If Migration with Network Migration, choose “Enter new network settings for one or more destination nodes”. Then, on subsequent screens, you will be allowed to change the hostname, IP, subnet mask, and gateway for the new server.

8. Create Migration Task – choose the iso to install on the new VMs, and choose the time the migration will occur.

It will ask you for a Bootable ISO file.

Login into a Filezilla client or Winscp using the IP address of PCD and credentials as:

Username: adminsftp

Password: < Pcd password >

The file path should be /fresh_install

and you can define a migration procedure as well.

You can configure an email address in case of a successful and failed Migration task.

Post-Migration Tasks

  • Update VM Tools
  • Ensure dbreplication is up and running for all nodes and does not have any errors.
  • Perform testing for local/national/international calling.
  • Perform testing for all phone features like conference, barge, transfer, DND.
  • Ensure you have NTP sync with stratum value less than 3 for Publisher as the subscribers take Publisher as NTP reference and every subscriber will be using stratum value which will be NTP pub’s + 1.
  • Timelines à Publisher can take up to 3 to 4 hours and subscribers can take 2-3 hours for upgrade.

This was just a normal plan in upgrading/migrating Cisco CUCM from the 8.5 version to 12.5. The article’s intention is to provide you a basic approach on how to plan and upgrade your system.

We hope this article gives you an understanding of the Cisco Mobile and remote access (MRA).

Are you looking for consulting, advisory and professional services to deploy a Collaboration Environment for your organization? Zindagi can help. 

Zindagi Technologies Pvt. Ltd. is an IT consultancy and professional services organization based out of New Delhi, India. We have expertise in planning, designing, and deployment of collaboration environments, large-scale data centers, Private/Public/Hybrid cloud solutions. We believe in “Customer First” and provide quality services to our clients always. Give us a call on +91 97739 73971.

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