Subaru Legacy Owner's Manual page 256

Siri
If required to say more, the system will notify you with
the beep sound. Continue speaking.
If the system fails to recognize what is being said, or
to request a different operation, select
the talk switch.
To cancel Siri, select
Cancel
hold the talk switch.
NOTE
Siri cannot be started while placing or receiving hands-free
calls with your iPhone and iPod touch (including while holding
incoming calls), or while having a hands-free conversation.
Siri cannot be used while using the system's voice recognition
function. Start Siri after exiting the voice recognition function.
The system screen will display the calling screen when a hands-
free call is placed.
Unit operation while using Siri will differ depending on your
iPhone or iPod touch.
Siri may not recognize what is being said if:
Spoken too quickly.
Spoken at a low or high volume.
Driving with a window open.
Passengers are talking while using Siri.
The air conditioning speed is set high.
When air from the ventilator blows directly toward the
microphone.
254
NOTE
, or press
(Cancel), or press and
ABOUT THE SUPPORTED DEVICES FOR Siri
This system supports the following devices.
In the following conditions, the system may not recognize what is
being said properly, and use of Siri may not be possible.
What is being said is incorrect or unclear. Note that certain
iPhone or iPod touch to recognize.
There is excessive background noise, such as wind noise.
Functionality offered by Siri is dependent on the iOS version,
prior notice.
Supported iOS versions
iOS6 or later (6, 7)
Supported models
iPhone 5
iPhone 4s
iPod touch (5th generation)