The call ID is a call's reference number, a bit like its ID card. When you want to report a problem, you need this number to ensure that the issue can be properly investigated.
Click on the tab for your call history, represented by the clock icon (highlighted in red), and then click on the line of a call to go to the call record.
The Call ID is located at the bottom of the call card (highlighted in red). Click on the copy button, located to the right of the Call ID, to copy this number, and send it to Ringover Support to report your issue.
Go into your Web app and, access your past calls, and click on the call you want. On the call card, locate the Call ID at the bottom (highlighted in red) and click on the copy button, located to the right of the Call ID, to copy this number.