Lexus GS 450h 2008 Owner's Manual page 309

Status display
You can check such indicators as signal strength and battery charge on
the "Telephone" screen.
Indicators
Connection status
Battery charge
Call area
Signal strength
3-4. Using the hands-free system (for cellular phone)
Connection status
Battery charge
Call area
Signal strength
Conditions
Blue: Good
Yellow: Bad
: Not connected
: Full
: Low
"Rm": Roaming area
"Hm": Home area
: Good
: Bad
: Not connected
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