How do I join a call in progress, after being late to pick up the call, and getting a "Missed group voice call" notice? I tried calling back the call initiator, and she was presented the choice of ending the call in progress and then picking up my call, or continuing the call in progress and rejecting my call.
I've been used to doing this with the standard "Phone" app, which gives me three choices:
(1) pick up the new call and end the call in progress
(2) pick up the new call, putting the call in progress on hold, and then join the new call to the call in progress
(3) reject the new call, continuing the call in progress.
According to WhatsApp Help Center for Android, you can only end your current call and accept the incoming call, or decline it. Unfortunately, it is not possible to put your current call on hold and accept the incoming call if you're using an Android device.
Edit: You can only put the current call on hold and accept the incoming call if you're using an iPhone in case someone calls you from outside of WhatsApp. (Help Center for iPhone)