I want to write a sample demo using OpenCTI API for Lightning Experience. The URL I mentioned in the CallCenter's Adapter URL refers to a page developed using JSPs and served from a third-party domain. So, based on the documentation below, I connect to the OpenCTI API using the script-Tag.
<script src="https://c.<yourInstance>.visual.force.com/support/api/40.0/lightning/opencti_min.js" type="text/javascript"></script>
N.B. Salesforce documentation: Connect To OpenCTI
The problem is, that at page load, the browser-console logs the following exception message: "uncaught exception: Failed to initialize Open CTI. Ensure that it is loaded from the right frame with correct URL parameters".
As subsequent problem, all OpenCTI functions return with error.
What am I doing wrong?