R200 How to bridge LAN/WAN ports and still get Voip

Hi Guys

I am trying to figure out how to bridge the LAN and WAN ports so the voip can still work.

When I put the unit into bridge mode I cannot find where to put the DNS server address or Gateway of the rooftop radio.

Attached is a diagram of what I wish to do. 

Your assistance is much appreciated.

Please check this post , should be of help .


Thanks that looks to be most helpful