Configuring Calling Encryption Between Cisco IP Phones and Cisco Unity Connection

Paul Smith
Senior Engineer I

This blog is one of five dealing with the encryption of various Cisco UC devices.  This particular piece deals with setting up encrypted calls between phones on a cluster and Cisco Unity Connection.  The other blogs in this series are, Configuring Calling Encryption Between Cisco IP PhonesConfiguring CUCM with Secure LDAPConfiguring Secure Hardware Conferencing, and Configuring a Secure Voice Gateway.  The information in the LDAP article stands on its own, but the steps in “Configuring Calling Encryption Between Cisco IP Phones” must be followed before one can configure any of the items in the other pieces.

The steps detailed in these blogs may not be the final word on all of the ins and outs of configuring the items.  However, we discovered that there are very few – or no – articles dealing with these subjects written by someone who has actually performed the tasks.  We therefore felt it would be a service to offer information about the steps that worked for us in our specific set of circumstances (particularly since we, apparently, fell into most of the traps).

Comments are welcome and we will be happy to update these blogs if need be.

  1. The first three tasks are to run the CTL client, configure secure phones and set up Unity Connection.  These three tasks are outside the scope of this document, but the first two are covered in the article “Configuring Calling Encryption Between Cisco IP Phones”.
  2. Next, get the root certificate from the CUC Publisher.  On CUC it’s a little different from the way it is in CUCM.  Log into Unity Connection Administration and navigate to Telephony Integrations > Security > Root Certificate.  On the link below the certificate that says, “Right Click”, right click and select “Save Target As”.  The trick here is that Windows will try to save this as an .htm file.  You must change the extension to .0 (that’s a zero).  Save the file to your PC.
  3. Next, go to CUCM OS Administration and upload the file from CUC.  Navigate to Security > Certificate Management and click the “Upload Certificate” button.  In the new window say that you’re installing the certificate as a CallManager-trust.  Do this on all of the servers running the CallManager service.
  4. While you’re in CUCM, go over to the main CUCM Administration page and navigate to the place where your voicemail ports were created (they’re now in different locations on different versions of CUCM).  Click the link for the first port and in the Device Security Mode drop-down set it as either Authenticated or Encrypted (we chose Encrypted).  Click Save and Apply.  Repeat this step on every voicemail port.
  5. The final CUCM configuration is to go to the Serviceability page, navigate to Tools > Control Center – Feature Services, select the publisher, and restart the Cisco Certificate Authority Proxy Function service.  Note that the service only runs on the publisher.
  6. Back in Unity Connection Administration, go to Telephony Integrations > Port.  Select each port and set the Security Mode to either Authenticated or Encrypted.  We chose Encrypted.  Whichever you choose, remember that it must be the same as what you chose when you configured the ports on CUCM.  What’s kind of a “gotcha” here is that when the port’s Security Mode is changed, you then have to look near the top of the configurations for the port and hit the Restart button next to the “Port Name” window.  This one took us a little while to figure out.
  7. Next go to Telephony Integration > Port Group.  Select the port group that’s configured and then go to Edit > Servers.  In the servers list make sure there’s an IPv4 address for every server in the CUCM cluster.  If not, add the ones that are missing.  Finally, on the main page of the port group, reset the port group.

At this point you should be done.  Look back at CUCM and if the ports come up as being registered, you’re set.  If they don’t, go back over steps 1-7 carefully.  The final test is to hit the Messages button on one of your secure phones and make sure that when CUC answers, the lock icon is displayed next to the caller ID just like it is when you make a secure call.

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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.