I am experiencing calls being merged between what'sapp calls and network calls involuntarily. When I answer Whatsapp call, then another call comes in through the network and I answer it, Whatsapp no longer is placed on hold but rather merges the two calls as a conference call or a multiple participant call. Is there a feature to place Whatsapp call on hold, or must I hang up before answering network call to ensure the calls are not merged/conferemced? I have Whatsapp version 2.18.79.