CTI = Computer Telephony Integration. I don't think that this is the actual cause of your problem unless there is something I don't know about your situation. Here is what the CTI Manager Service does:
The CTI Manager contains the CTI components that interface with applications. With CTI Manager, applications can access resources and functionality of all Cisco CallManagers in the cluster and have improved failover capability. One or more CTI Managers can be active in a cluster, but only one CTI Manager can exist on an individual server. An application (JTAPI/TAPI) can have simultaneous connections to multiple CTI Managers; however, an application can only use one connection at a time to open a device with media termination.
CTI Manager is required in a cluster for applications that use TAPI or JTAPI Computer Telephony Integration (CTI). The CTI Manager acts as a broker between the CTI application and the Cisco CallManager Service. It provides authentication of the application and enables control or monitoring of authorized devices. The CTI application communicates with a primary CTI Manager and, in the event of a failure, will switch to a backup CTI Manager. The CTI Manager should be enabled only on call processing subscribers, thus allowing for a maximum of eight CTI Managers in a cluster. Cisco recommends that you load-balance CTI applications across the various CTI Managers in the cluster to provide maximum resilience, performance, and redundancy.
Here are the primary CTI Services on the CCM:
Cisco IP Manager Assistant
When activated, Cisco IP Manager Assistant enables managers and their assistants to work together more effectively. Cisco IPMA supports two modes of operation: proxy line support and shared line support. The Cisco IPMA service supports both proxy line and shared line support in a cluster. Refer to the Cisco CallManager Features and Services Guide.
The feature comprises a call-routing service, enhancements to phone capabilities for the manager, and desktop interfaces that are primarily used by the assistant.
The service intercepts calls that are made to managers and routes them to selected assistants, to managers, or to other targets on the basis of preconfigured call filters. The manager can change the call routing dynamically; for example, by pressing a softkey on the phone, the manager can instruct the service to route all calls to the assistant and can receive status on these calls.
Cisco CallManager users comprise managers and assistants. The routing service intercepts manager calls and routes them appropriately. An assistant user handles calls on behalf of a manager. Cisco IPMA comprises features for managers and features for assistants.
Cisco WebDialer Web Service
Cisco WebDialer provides click-to-dial functionality. It allows users in a Cisco CallManager cluster to initiate a call to other users inside or outside the cluster by using a web page or a desktop application. Cisco WebDialer provides a web page that enables users to call each other within a cluster. Cisco WebDialer comprises two components: WebDialer servlet and Redirector servlet.
The Redirector servlet provides the ability for third-party applications to use Cisco WebDialer. The Redirector servlet finds the appropriate Cisco CallManager cluster for the WebDialer user and redirects the request to the WebDialer in that cluster. The Redirector functionality only applies for HTTP/HTML-based WebDialer client applications because it is not available for Simple Object Access Protocol (SOAP)-based WebDialer applications.
If starting/stopping the CTI service seems to resolve your problem, then I would ask if these phones are being controlled or monitored by any CTI applications (ex: IPCC/IPCCX)...if not, then I would be suspicious of a bug or something else at play. Do you have up-to-date TAC support for your system?
Hailey
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