Native Android applications also use Intents to launch Activities and sub Activities
ACTION-ANSWER Opens an Activity that handles immediately initiates a call using the number supplied in the Intent URI. Genereally it's considered better from to use ACTION_DIAL if possible.
ACTION_DELETE Starts an Activity hat lets you delete the data specified at that Intent's data URI.
ACTION_DIAL Brings up a dialer application with the number to dial pre-populated from the Intent URI. By default this is handled by the native Android phone dialer.
ACTION_EDIT Requests an Activity that can edit that data at the specified Intent URI.
ACTION_INSERT
ACTION_PICK
ACTION_SEARCH
ACTION_SENDTO
ACTION_SEND
ACTION_VIEW
ACTION_WEB_SEARCH