Block Whatsapp Voice Calling

We are using Whatsapp (Android) to communicate with our customers and would like to block the Voice Calling (VOIP) feature on the app since we route all voice calls through our PBX.

I do not want to use older version of the app as suggested on some Inteet Forums, and since Whatsapp does not provide the settings to disable Voice Calling, can you please suggest what are the other ways to achieve this ?

Are there specific ports which I can block on my router or Whatsapp uses random ports each time ?

Does lowering or changing any other Qos Setting on the router has anything to do with this ?

Thanks a lot