On the User Management section, there is a column- Permission Status.
This gives you an indication of whether or not the permissions on the device are set up correctly to allow for Salestrail to run in the background of the device.
If permissions and battery settings are incorrect, then call logging will most likely not occur.
If you have one or both of the notifications seen below on your Salestrail app, the notification status on the dashboard will be red. Click on the permissions notification to enable the required permission and the battery optimization notification to change the battery settings to Unresrticted/ Not Optimised or Allow salestrail to run in the background