TOYOTA 2011 Tundra - Manual (Page 450)

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3-5. Using the hands-free phone system (for cellular phone)
n Automatic volume adjustment
When vehicle speed is 50 mph (80 km/h) or more, the volume automatically
increases. The volume returns to the previous volume setting when vehicle
speed drops to 43 mph (70 km/h) or less.
n When using a voice command
For numbers, say a combination of single digits from zero to nine, # (pound),
∗ (star), and + (plus).
Say a command correctly and clearly.
n The system may not recognize your voice in the following situations:
l When driving on a rough road
l When driving at high speeds
l When air is blowing out of the vents onto the microphone
l When the air conditioning fan emits a loud noise
n Operations that cannot be performed while driving
l Operating the system with
l Registering a cellular phone to the system
n Changing the passkey
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