The mobile phone displays high definition, indicating that the VOLTE service has been opened. VOLTE is a high-definition voice and video calling service based on 4G network. There is no function fee for opening the VoLTE function.

Advantages and disadvantages of mobile phone with high definition: 1, which can keep the Internet access of 4G network while making phone calls, and also has the advantages of twice improvement of sound quality and low drop-off rate. 2. At present, only some cities in China have launched trials of VoLTE services of different operators, and different mobile phone manufacturers need to update their mobile phone system files to support the opening. At present, China Mobile VoLTE HD voice calls are the same as ordinary local calls; The difference between China Unicom and China Mobile is that when China Unicom VoLTE has the function of high-definition voice and video, it will consume users' traffic while charging normal phone bills.