Activity Action: Perform a call to someone specified by the data.
Input: If nothing, an empty dialer is started; else Intent.Data is URI of a phone number to be dialed or a tel: URI of an explicit phone number.
Output: nothing.
Note: there will be restrictions on which applications can initiate a call; most applications should use the Intent.ActionDial.
Note: this Intent cannot be used to call emergency numbers. Applications can dial emergency numbers using Intent.ActionDial, however.