1. A flashing red signal strength indicator means that the SIM card is missing or not installed properly.
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  2. Remove the bottom cover of your AT&T Wireless Internet and the back-up battery. Make sure the SIM card is pushed all the way into the SIM card slot and is secure.
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  3. SIM card may be invalid or damaged and need to be replaced. For a replacement SIM card, take your AT&T Wireless Internet device to your local AT&T store. Or, call AT&T Customer Care at 1-800-331-0500.
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