Native Android applications allow Intents to launch Activities and Sub-Activities.
=> + content://contacts/people/ -- Display a list of people, which the user can browse through.
=> +tel:123 -- Display the phone dialer with the given number filled in. Note how the VIEW action does what what is considered the most reasonable thing for a particular URI.
=> +tel:123 -- Display the phone dialer with the given number filled in.
ACTION_EDITcontent://contacts/people/1 -- Edit information about the person whose identifier is "1".
ACTION_GET_CONTENTwith MIME type
vnd.android.cursor.item/phone-- Display the list of people's phone numbers, allowing the user to browse through them and pick one and return it to the parent activity.
ACTION_CALLBring up a phone dialer and immediately initiates a call using the number suplied in the data URI. In generally, it's considered better form to use the DIAL_ACTION if possible.
ACTION_DELETEStart an Activity that lets you delete the entry currently stored at the URI location.
ACTION_ANSWEROpen an Activity that handles incoming calls. This is handled by native phone dialer.