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Similar experience. My iPhone 6s just received no service about 9.30am. I am currently on a sim only with EE and use it in this phone. Therefore I call Ee and they recall my imei number and they confirm Vodafone has blocked it and I will need to contact them to resolve it. This phone was purchased 2-3 years ago through apple direct. Only thing I can think off is when I’ve allowed friends to make a call with my fone using their Vodafone sim whilst there batteried died. Vodafone blacklist team has received 2 emails so far; one from Inside Vodafone store & one from customer service. They said give it 48 hours. Let’s see what happens.