HTC ThunderBolt Manual page 11

2. Insert the 4g SIM card (with the cut-off
corner first and the gold contacts facing
down) into the SIM card slot.
note: a Subscriber Identity Module (SIM card) is a "smart
card" that houses personal information, such as your mobile
phone number, calling plan, account information, and
content, such as contacts, text messages, and call history.
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