i just want to explore whether full duplex voice communication works on zigbee
No, not enough bandwidth.
You are being very vague.
It depends on what you want to do. Do you want to build your own transmitter or do you want to use ready built modules?
A lot depends on where about in the world you are as the regulations differ from country to country. Most places don't allow you to make transmitters, even on the license free bands. These transmitters must be type approved. That is the design must be tested in a recognised test house.