Hello Rickard,
Unfortunately, there are not enough details here to identify a specific problem. In case it helps, here is some general advice.
In the USD development paradigm, Hosted Controls have Actions, which serve as inputs, and Events, which serve as outputs. The application framework uses Actions to send commands to Hosted Controls, and those applications can fire Events to "bubble
up" information to the framework, often triggering further Actions. Instead of using Events, CTI implementations frequently use CtiLookupRequests in their code, which further involve Window Navigation Rules in their configuration.
Raising Events from code in USD is fairly simple, however there are two components. In the code, there must be a FireEvent command. In the Configuration, the Hosted Control must have an identically-named Event, and of course the Event must be
related to any necessary Configuration record.
If you're using the CTI template for Visual Studio, make sure your configuration is using all three CTI components: a connector, a control, and a desktop manager. All are created by the VS project template.
If the ISV has supplied a CTI Hosted Control and additionally provided the source, it may be helpful to troubleshoot the CtiLookupRequest and surrounding code. Unfortunately, it's more likely that the issue in the configuration rather than the code,
if not both. Regardless, the USD Debugger will prove itself to be indispensable here.
Are you able to clarify your issue?