There are Communication entries and 3 scheduling views in EQ that use the common Actions list.
To begin you need to decide which actions will be used on the Diary, Resource Planner or Schedule.
Click the arrow under the Appointment Diary toolbar button:
Select Actions to show this screen:
Work through each Action and tick or un-tick these columns:
Show on EQ Schedule - It is recommended to show Deliveries
Show on EQ Diary - It is recommended to show actions such as Appointment, Call, Reminder, Visit
Show on EQ Resource Planner - It is recommended to show actions such as installations, fitting, plumbing, electrician trades etc.
Click 
Update to save and close.
Regardless of which diary views are ticked, all Communication entries for all Actions will be shown in the Customer List, under Communication and the Projects Communications screen.