Whether WIFI can be connected to the Internet and the phone has no phone charges, there is no relationship between half a cent. Even if you don't have a mobile card, you can still surf the Internet as long as your phone is connected to a WIFI network. No phone charges only affect your phone calls and mobile Internet access. WIFI comes with the phone and has nothing to do with the phone bill.
After the call is finished, you can continue to use free Wi-Fi as long as you leave your phone on. Once it is turned off and turned on, the operator automatically identifies the user card as unable to register, and can no longer use Wi-Fi.