What does HD next to China Mobile mean?

HD refers to high-definition voice, which is a free upgrade of ordinary telephone service. VoLTE service, like calling and texting, is a free basic service function that mobile phone numbers automatically enjoy, and there is no function fee.

High-definition voice can make your voice clearer and dial faster when you make a phone call, and if you often use your mobile phone to surf the Internet, you can also surf the Internet while making a phone call without interfering with each other.