Under normal circumstances, staying in the epidemic area for more than 4 hours will be recorded by the travel card. It's useless to turn off your mobile phone card, because the base station will detect the last message before you turn it off and it will be recorded. Moreover, if we stay in the epidemic area for a long time, the shutdown will affect our travel life, at least we can't open the health code.
The removal of the mobile phone card has little effect on the travel code. If the mobile phone card is not returned to the mobile phone, the signal base station will not detect our location information and the travel code record will not be updated.