assets/carrier_config_21902.xml

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<carrier_config_list>
    <carrier_config>
        <string-array name="non_roaming_operator_string_array" num="1">
            <item value="21901" />
        </string-array>
    </carrier_config>
</carrier_config_list>