What is HD displayed on a mobile phone? Does it cost money? , how to cancel

HD is displayed at the top of the mobile phone screen, indicating that China Mobile VoLTE high-definition voice service is enabled. If you need to cancel, go to Settings-(More Connection Settings)-Mobile Network-HD Voice-Turn off.

VoLTE is Voice over LTE. It is an IP data transmission technology that does not require a 2G/3G network. All services are carried on the 4G network, which can realize the unification of data and voice services under the same network. In other words, 4G networks not only provide high-speed data services, but also provide high-quality audio and video calls, and the latter requires VoLTE technology.