After upgrading to iOS 11 on my iPhone 7 Plus, I started getting USSD (edit: looks like this is called "flash SMS", not USSD) popups (see below). If I tap "Accept", the popup goes away, but it shows up again very quickly. I'm currently in India, and this is happening on Airtel (an Indian carrier). When I use my roaming AT&T SIM instead, I don't see these popups. Does anyone know how I can fix this problem with my Airtel SIM?
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