1. Introduction to ClickToCall.msi

This essential Windows Installer package enables enterprise-grade click-to-call functionality within Cisco Unified Communications Manager (CUCM) environments. Officially released under Cisco’s Extended Security Maintenance program in Q1 2025, version 4.5(1) introduces TLS 1.3 encryption for web-initiated call requests while maintaining backward compatibility with CUCM 12.5(1)SU6 through 14.5(1) clusters.

The software integrates with Cisco Unified Personal Communicator and Webex Calling hybrid deployments, resolving 12 CVEs identified in previous implementations. It supports automatic number formatting for 40+ country codes and maintains a 50-entry call history archive with SHA-256 hashed storage.

2. Key Features and Improvements

​​A. Security Enhancements​​

  • FIPS 140-3 validated encryption for call metadata
  • XSS vulnerability remediation in web callback interfaces (CVE-2024-32895)
  • Automatic certificate rotation via Cisco PKI Service Module 3.2

​​B. Protocol Support​​

  • Dual-stack IPv4/IPv6 session initiation
  • WebRTC gateway integration for browser-based calling
  • Enhanced SIP OPTIONS keepalive (30-300s configurable range)

​​C. Enterprise Integration​​

  • Microsoft Teams direct routing compatibility
  • Salesforce CTI adapter pre-configuration templates
  • VMware Horizon VDI optimization profiles

3. Compatibility and Requirements

Component Supported Versions Notes
CUCM 12.5(1)SU6 – 14.5(1) Requires Prime Collaboration 12.6.2+
OS Windows Server 2019/2022 .NET 6.0.28+ required
Browsers Chrome 120+, Edge 120+ WebRTC mandatory
Security Cisco Trust Agent 2.1+ FIPS mode enabled

​​Critical Dependencies​​:

  • 2GB RAM minimum per call processing node
  • NTP synchronization (±500ms cluster-wide)
  • TLS 1.2/1.3 enforcement for web services

4. Limitations and Restrictions

  1. ​​Platform Constraints​​
  • No support for Windows Server Core installations
  • Maximum 50 concurrent web sessions per node
  1. ​​Feature Restrictions​​
  • Third-party certificates require manual trust chain upload
  • Call history archives limited to 90-day retention
  1. ​​Virtualization Notes​​
  • VMware vMotion operations restricted during active calls
  • Requires VM hardware version 17+ on ESXi 7.0U3+

5. Obtain ClickToCall.msi

Authorized Cisco partners with active UCSS contracts can access this package through:

  • ​​Cisco Software Center​​: Requires Unified Communications Manager Service Package entitlement
  • ​​IOSHub Enterprise Solutions Portal​​: SHA256-verified copies available (MD5: 8d969eef6ecad3c29a3a…)

For deployment verification:
Cisco TAC Collaboration Support: +1-800-553-2447 (Ref: CTC-451)
IOSHub Priority Access: [email protected] ($5 service verification fee applicable)

This critical communication package reduces average call setup time by 40% in validated deployments. Always validate cryptographic signatures against Cisco Security Advisory cisco-sa-202501-clickcall before implementation.

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