Thereare two kinds of conferences available in the basestation model ofFreeSpeak/CellCom. Of the ten Conferences shown in the GROUPS tab in theConfiguration Editor, the first five are called Groups and six through ten arecalled WPL, or Wireless Party Lines.
Fixed Group: Thinkof a group as if you are looking at your open hand (seeing the palm-side).Let's say that the thumb is you calling the group. All the fingers hear you,whether they have a listen opened to you, or not.This is like a point-to-pointform of communication, but think of it as one-to-many. And when the"ring-finger" replies, only you (the "thumb") hears thatreply. So the originator of the call gets heard by all members of that group,but the "replyer" is only heard by the originator. The upside is thatone need not have their "listen" turned on to hear the call.A group can be made up of wireless users and any interface wired to the basestation 
WPL, or Wireless Party Line
Ina Wireless Party Line, however, everyone listening will hear anyone who is talking onthat PL. They must have selected a LISTEN path so they will be able to hear thePL.A WPL can have both wireless and wired users. however wired users (interfaces wired to the basestation are force into the WPL as fixed members.. these means they are forced to listen and talk into the WPL at all times).but the CellCom wireless BPs are PROGRAMMED to have a key to access the WPL.. so that they can decide when to talk or listen to the WPL.
Additionally,and most importantly, in the case of the Cellcom basestation system, is that eachWPL has its own cross point, as opposed to the GROUPS, which share a crosspoint This means that one can turn down the listen on a WPL to a point that one nolonger hears that WPL, but if one is a member of more than one"group", and one turns down  one of the groups, they will ALL godown a bit, but never go ALL THE WAY down, unless they are ALL TURNED DOWN.