android_device_xiaomi_sm8450-common/overlay/FrameworksResCommon/res/values-mcc311-mnc480/config.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright (C) 2024 The LineageOS Project
     SPDX-License-Identifier: Apache-2.0
-->
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
    <!-- If Voice Radio Technology is RIL_RADIO_TECHNOLOGY_LTE:14 or
         RIL_RADIO_TECHNOLOGY_UNKNOWN:0 this is the value that should be used instead.
         A configuration value of RIL_RADIO_TECHNOLOGY_UNKNOWN:0 means
         there is no replacement value and that the default assumption
         for phone type (GSM) should be used. -->
    <integer name="config_volte_replacement_rat">6</integer>

    <!-- Flag specifying whether VoLTE should be available for carrier: independent of
         carrier provisioning. If false: hard disabled. If true: then depends on carrier
         provisioning, availability etc -->
    <bool name="config_carrier_volte_available">true</bool>
</resources>