How to use the VoLTE (Voice Over LTE) video call?

Here are the steps:
Go to Contact > click the contact you want to have video call with > click Video call icon on the right side of the contact.
Notes: the following requirements must be met:
1. Both parties support the VoLTE(4G Calling) function and video call function.
2. The SIM card has been opened for VoLTE business.
3. VoLTE function has been opened.
4. Support VoLTE network in the location.
5. Only under the operator VoLTE network (Jio and Jio, Vodafone and Vodafone) can make video calls.