Hi,

I'm trying to create a Softphone on VisualForce and add it to Lightning app in utility bar.

However, when I add open cti script I recieve error as in the subject:
Uncaught Failed to initialize Open CTI. Ensure that it is loaded from the right frame with correct URL parameters

Page code

<apex:page showHeader="true" sidebar="true">
    <apex:includeScript value="/support/api/40.0/lightning/opencti_min.js"/>
</apex:page>

Anyone else had similar problems?

Regards,
Karol