You can add the call extension data from AdWords into the report in two different ways.

You can load the call data in the report by setting the dimension to "Call Extension" as shown in the screenshot below

This will load your call extension data with one phone number in each row

You can show call data by segmenting any data(campaigns, ad groups etc) by "Click Type" as shown in the screenshot below

This will help you show which campaigns, ad groups, keyword etc are driving the phone call data.