Note: In a GSM network the dialer observes call operations from RIL call state changes; however, in a CDMA network RIL call states do not change under some call operations, so HFP devices need this additional method to have the dialer to be informed of the operation.
var request = instanceOfBluetoothAdapter.answerWaitingCall();
DOMRequest object to handle the success or error of the operation.
Not part of any specification yet. It should be discussed as part of the W3C's System Applications Working Group.