Hi Polina,
If I understand correctly voice chat is meant to be used when there is someone physically at the host location. My situation is I am connected to the host computer via RU. Local xxxx calls local yyyy (my phone at the host location). The host computer connected via VOIP and using jabber gives me the option to answer the call. I hear the caller of course because the sound from the host computer is being transferred to the remote computer via RU. They don't hear me because the mic on the remote computer is not being pushed to the host computer, or so it would seem.
I tried voice chat but that does not seem to allow me to have full control of the computer, which I need. After starting voice chat, I clicked the full control button in the options box, but I am not sure of that still leaves me in voice chat, or if has switched to full control outside of voice chat.