PC World - Until early June, AT&T had an online tool that helped iPad 3G owners sign up for its mobile Wi-Fi service: Users typed in the 19-digit serial number for their iPad's micro-SIM card, also known as the ICC-ID (integrated circuit card identifier), and the site returned the e-mail address that the owner had used to verify registration. AT&T used that e-mail address to populate a log-in field on the *** registration form.
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