This is most likely because your phone has the MAC address randomization setting enabled. In this case, each time the device’s MAC address is connected to a network, it may change and require re-identification. To avoid having to confirm your phone number constantly, you need to go to the MT_FREE network’s additional settings and change them as follows:
- for Android in the «Privacy» point you need to select the value of «MAC-address of the device»;
- for OS, depending on the version of the operating system, you need to disable the «Private Wi-Fi Address» setting or set its value to «Off».