You need to have friends or projects (created by yourself and joined projects)
During a single chat or a shared chat on a project, you can choose to turn on voice calls in order to facilitate communication. Users with voice calls turned on can hear what is being said between them as if they were talking on the phone.
Note:The number of voice call hours per user per month is allocated by the system based on the type of membership, and you can view the voice call usage on the membership information page.
The voice call feature will not be turned on when the voice call hours are exhausted, but will not affect the use of other features of the program.