SIGNAL STRENGTH: Indicated relative signal strength where:
– 0 LEDs: Unacceptable; Signal strength is very weak or not detectable
– 1 LED: Weak
– 2 LEDs: Moderate
– 3 LEDs: Good
– 4: LEDs: Excellent
Not very detailed, however, the exact RSSI value can be obtained via the WebUI Information > Mobile page or via the "display mobile" CLI command.