Quick Filters.
Quick filters are available at the top of the activity list to help you get to specific activities quicker. You can choose from Missed Calls, Voicemails, SMS or Flagged Items and the activity display with show only the items you selected. A volume indicator is included in the quick filter so you can see how many of each item you have in your activity feed.
To apply a quick filter, select the required filter and only the results selected will be shown.
To remove a quick filter, simply press the quick filter item selected and all results will be displayed.
Advanced Filters.
For more advanced filtering options, a filter icon is included at the top of the activity list, this will allow you to choose from more options to filter on than the quick filter.
Select the filter icon to display a list of options and apply the filters you require and then press the 'x' icon to return to the activity feed.
To remove any advanced filters apply, select the filters icon and press the 
icon to remove all checkboxes. Press the 'X' button and return to the activity feed.