UM troubleshooting, "No Network Coverage"

[inquisitor]

A GSM phone won't pick up or show a signal unless it is registered on a network, which in turn requires the SIM card to be admitted. So without roaming agreement with any of the locally available networks your phone won't register on any network. USSD-commands make no sense without network connection. But you can see a list of available GSM networks if you do a manual network search.