Handsfree hierarchy
===================

Service		org.ofono
Interface	org.ofono.Handsfree
Object path	[variable prefix]/{modem0,modem1,...}

Methods		dict GetProperties()

			Returns properties for the Handsfree Interface. See the
			properties section for available properties.

		void SetProperty(string property, variant value)

			Changes the value of the specified property. Only
			properties that are listed as readwrite are
			changeable. On success a PropertyChanged signal
			will be emitted.

			Possible Errors: [service].Error.InProgress
					 [service].Error.InvalidArguments

		string RequestPhoneNumber()

			Request a phone number from the AG, corresponding to the
			last voice tag recorded in the HF. The AG may accept or
			reject this request depending on its internal state.

			This functionality is generally implemented by using
			the +BINP=1 AT command.

			Possible Errors: [service].Error.InProgress
					 [service].Error.InvalidArguments
					 [service].Error.Failed

Signals		PropertyChanged(string property, variant value)

			Signal is emitted whenever a property has changed.
			The new value is passed as the signal argument.

Properties	array{string} Features [readonly]

			List of features supported by the AG. The currently
			supported values are:
				"voice-recognition"
				"attach-voice-tag"

		boolean InbandRinging [readonly]

			Boolean representing whether inband ringing is enabled.

		boolean VoiceRecognition [readwrite]

			Boolean representing whether voice recognition is
			currently active in the AG. This property may be written
			to activate or deactivate the function from the HF, or
			the AG could autonomously initiate it.