CUPC Cannot Control Desk Phone – Another Reason Why

Paul Smith
Senior Engineer I

paul_smithWhen the CUPC application is being rolled out, one of the things that seems to make administrators go nuts is the fact that the authentication that looks like it’s taking place when a user logs in is only partial authentication. Eventually administrators discover the spot to go within CUPC to add more usernames and passwords to make the client interact with voicemail applications and web meeting applications. But the control of the desk phone is the oddest thing. There are no extra credentials that can be entered to make it work, it’s often the case that when an administrator goes to Help > Show Server Health, he or she sees an error stating that CUPC failed to connect to the desk phone because of invalid credentials.


This tends to happen when CUCM is using Active Directory LDAP for authentication. A well-documented fix for the problem is to make sure that the LDAP servers being referenced are Global Catalog servers, and that the port number used is 3268 (or 3269 for secure Global Catalog connections).


But pointing to a non-Global Catalog server might be only one cause of the problem. We ran into another one a little while ago. The only reference to it was in Bug Case CSCtk62723, which states that it was first noticed in CUCM version 8.0(2.10000.24), but we’re here to tell you that it showed up in a client’s 6.1(3.3190-1) system too. Notice this is the CUCM version, not the version of CUPS. The problem is in the End-User Credential Policy; one of its parameters causes the policy to be a bit wonky when it communicates with CUPC in an LDAP integrated environment.

“Wonky,” by the way, is a technical term that I learned at a very prestigious University.

The “Inactive Days Allowed” parameter is the issue. Because users are authenticating to LDAP and not a database within CUCM, the policy has no way of knowing how much time has passed between End-User logins. When the number of days set in the parameter expires, certain types of authentication can be shut down. So far, the only time we’ve seen this is during the credential exchange with CUPC when that application tries to take control of a desk phone.

Notice, too, that this will only affect users that have been on the system longer than the number of days stated in the parameter. This is why new “test” users we created as part of the troubleshooting process all worked.

To fix the issue, we had to turn off LDAP Authentication by navigating to System > LDAP Authentication, taking the check mark out of the “Use LDAP Authentication for End Users” box, and saving.

Then we went into User Management > Credential Policy, selected each policy that controlled passwords, and deactivated the “Inactive Days Allowed” parameter by putting a “0” in its field.

Finally, we went back to LDAP Authentication and reactivated it by putting the check mark back in the box and saving. We also restarted the Cisco DirSync service for good measure.

According to the Bug case, this issue was fixed in later versions of CUCM v8. There’s no mention of whether it has been fixed in any newer versions of any other CUCM iteration. Because of this, we’ve thrown the issue in our hip pockets for possible future use in any other situation where authentication works…but only kinda.

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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.