To check abandon calls :
1. Click the shield icon 
on the left side of the screen, then under "LOGS" click on "Calls"
2. Once on the calls section page, click on "More Filters" located at the top ride side of the screen
3. Look for abandoned calls filter and then click on the dropdown and select "All abandoned calls" this will display only abandoned calls in the table.
NOTE : You may filter the period needed