Same problem. Cellular network is « error ». Gives me a notification that to call or receive call I have to update. So I updated to latest iOS 13.6 and still become no service. I Got angry and threw it Into the cupboard. [br]
Two days later the battery had drained so I charged it to full and when I opened it, it worked until someone called me and stoped midway between our calls and become no service again. So I put it to airplane mode again, drained the battery, left it the whole day then charged it the whole night While off and in the morning it was working. Again someone called me and stoped midway through the call and become no service. So I concluded that someone calling me is the problem since I was calling people and nothing was happening.[br]
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conclusion: I removed my SIM card and put in another which no one has my number and use it for cellular data. My Original SIM card Is in another phone that I use for calling only.