1. The Signal Strength LED displays the wireless signal strength that the AT&T Wireless Internet is receiving from the AT&T wireless network.
   
2. 3 or 4 bars indicate that the AT&T Wireless Internet is receiving a strong signal.
   Note: 1 or 2 bars indicates a moderate wireless signal.
   
3. Red indicates no wireless signal.
   Note: Red blinking indicates a SIM card error.
   
4. If the Signal Strength LED is red or only 1 or 2 bars are lighting up, move the AT&T Wireless Internet to a different location for best performance.
   Note: The Signal Strength LED will turn green when connected to LTE or blue if it is connected to HSPA/3G.