When you buy a new phone from AT&T Wireless, your eSIM or SIM card is set up and activated. However, when you switch to AT&T and bring your existing phone, you must activate your new SIM card before using your plan. This guide walks you through activating an eSIM and SIM card through AT&T. You can follow this guide whether you have an AT&T prepaid or postpaid plan from the carrier or a prepaid card from another retailer. These prepaid cards are a great way to save money alongside a budget Android phone.
