No cellular when calling

    Hi, My iphone is 5s. Recently, I updated my IOS to the latest version(10.3.3). Meanwhile, the t-mobile setting updated accordingly.(Carrier is T-Mobile 28.4 now. )However, after update, when I call someone, the cellular would disappear. The phone turns into absolutely no cellular mode. After I hang up the phone, the cellular would be back in 30 seconds to 1 mins.This thing never happen before. I waiting for 4 months after the new version IOS release so that I could avoid this situation. Unfortunately, it happened. Please help me to find the way to solve this issue. Thank you very much. I do need cellular and phone call work at the same time. Thank you.



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