On the left side of the "Permission Manager" you will click on a group to the left so it is highlighted. Then in the filter textbox we will type in "i_client_talk_power" this returns all the permissions with the word "i_client_talk_power" in it. The permission we are interested in is the "Client Talk Power". If this power is greater than 5, in this case it is, anyone in this group will be able to talk. To restrict which groups can and cant talk simply select the group you wish to restrict on the left side and make their "Client Talk Power" 4 or lower. Click on the Close button when finished.