There are a few things you can do to determine if someone is on a WhatsApp call. First, if the person is not using WhatsApp, they may not be able to see the call. Second, if the person is on WhatsApp, their phone may show that they are in a call but their chat box will not open. Third, if the person’s chat box opens but they are not in a call, it could be because they are using an app like Skype or FaceTime to make the call. fourth, if the person’s chat box does not open and they are in a call, it could be because someone else is calling them and their chat box is blocked.
