• Disabling the ability to make video and audio conversations through FacebookMessenger on the desktop is a simple process. Users can access the options menu by clicking the gear symbol in the chat panel on the right-hand side of the screen. 'Turn Off Video/Voice Calls' is an option there.People can also choose to turn the function off for a set amount of time or leave it off indefinitely.
• Unfortunately, there isn't a one-step method for stopping your phone from unexpectedly phoning your significant other or some random Facebook acquaintance. However, there is a solution to avoid the issue. Remove the microphone permission from your Facebook Messenger app's settings in 'System Preferences' on an iOS device.
•  Instead of placing the call, the app will ask for permission to access the microphone if the phone icon is touched.

Read More: How to Use & Manage Apple iPhone 6s Call Forwarding, Conferencing, Blocking, Caller ID, Call Logs settings