What's the contract for a BroadcastReceiver of PROCESS_OUTGOING_CALLS?

Hi,

I see that a BroadcastReceiver has a result_code, result_data, and extras which the developer of the receiver can use to communicate information back to the intent broadcaster, so that the broadcaster can use that to decide what to do next.

In the case of the broadcaster for the PROCESS_OUTGOING_CALLS intent, where can I read (link please) the written contract as to what it’s registered BroadcastReceivers are supposed to do (and can do) to affect the broadcaster’s behavior?

Thanks!