Cisco has recently unveiled Release 15 for its Unified Communications Manager (CallManager) and IM/Presence Service, marking a significant milestone in enhancing communication and collaboration experiences. In this blog post, we’ll delve into the key features, improvements, and important notes introduced in this release.

New and Changed Features

1.Migration to 64-Bit System

Release 15 introduces a major platform upgrade, transitioning all applications to a 64-bit system. This move aligns with industry standards, providing enhanced protection, security, innovation, and flexibility. It also eliminates memory bottlenecks associated with 32-bit architecture.

2. Auto Provision of Webex App and Cisco Jabber Devices

Unified Communications Manager now supports the auto provisioning of Webex App and Cisco Jabber devices when synchronizing new LDAP users from Microsoft Active Directory. This streamlines device management and enhances user experience.

3. Centralized Call History

Webex Calling for Microsoft Teams users can now view call history for shared devices registered to Unified Communications Manager. This feature enhances collaboration and integrates seamlessly with Microsoft Teams.

4. Certificate Revocation List Support

Enhancing security, Release 15 introduces support for certificate revocation lists in Unified Communications Manager. Administrators can enable this feature by checking the ‘Enable CRL’ checkbox and specifying the CRL Distribution Point URI.

5. Cluster Software Location

Making upgrades more efficient, Unified Communications Manager now allows centralized management of cluster nodes’ ISO files location. This simplifies the upgrade process and enhances overall system administration.

6. Device Mobility Support for Webex App on VDI

Starting from Release 12.5(1)SU7a, Unified Communications Manager supports using thin-client IPs for device mobility instead of Hosted Virtual Desktop (HVD) IPs for Webex clients. This provides better serviceability and debugging capabilities.

7. OAuth Enhancement: Eliminate Refresh Token Dependency on Publisher

The OAuth feature is enhanced to eliminate refresh token dependency on the Unified Communications Manager publisher node. This provides subscribers with the ability to update refresh tokens independently.

8. Enhanced Accessibility and Usability

The Cisco Unified Communications Manager Administration interface receives accessibility improvements, addressing tab sequencing issues, enhancing indexing for screen readers, and improving field label readability.

9. iOS Local Push Connectivity for Calls

Introducing Local Push Notification Service for iOS devices, Webex App minimizes call delays in Wi-Fi constrained environments. This ensures users receive calls promptly, even without internet connectivity.

10. SRTP DTMF Interworking

Release 15 enables Unified Communications Manager to invoke a hardware MTP (with SRTP DTMF interwork support) for a DTMF mismatch between secure endpoints. This improves DTMF translation for secure calls.

11. Cisco Unified Real-Time Monitoring Tool Enhancements

Unified RTMT can now be installed on workstations running Windows 11 or Linux using a single ‘’ plug-in. This streamlines installation and enhances flexibility.

12. Automatic Renewal of Refresh Token for Webex Clients

Unified Communications Manager now supports the automatic renewal of refresh tokens for Webex clients, enhancing security and minimizing manual intervention.

Important Notes

1. Deprecation of Remote Call Control with Microsoft Lync Server

Release 15 discontinues support for Remote Call Control with Microsoft Lync Server for IM and Presence Service. Users relying on this feature are advised to stick with Releases 12.5.x and 14 until their EOL/EOS.

2. Remove Deprecated Device Firmware from ISO

Starting with Release 15, phone firmware that has reached end-of-support will no longer be included in the Unified Communications Manager ISO. Administrators should be aware of this change during fresh installations.

3. New 2021 Signing Key

Release 15 onwards is signed with a new 2021 signing key. Administrators upgrading from versions prior to Release 14 may need to install the corresponding COP file for compatibility.

4. Simplifying Release Number Scheme

From Release 14 onwards, Cisco Unified Communications Manager adopts a single-number release plan. The traditional dot releases are replaced by Service Update releases published on top of the main major release.

5. New Cisco Gateway Support

Release 15 introduces support for several new Cisco gateways, expanding compatibility and providing users with more options for their communication infrastructure.


In conclusion, Cisco’s Unified Communications Manager and IM/Presence Service Release 15 brings forth a host of enhancements, ensuring a more secure, flexible, and user-friendly communication experience. Administrators are encouraged to review the release notes for a comprehensive understanding of the changes and plan their upgrades accordingly.