Hi,
Each Paging zone needs a port to be assigned and you need to look at feature access codes if you want to page zone wise separately. If you have access to system, commands to look at would be "display system feature-access" and "display system-parameters features" as well.
You would need a new trunk group if you have a separate paging system that is connected via the trunk group. If you want to use avaya phones for this feature, then you would not need a port/trunk group, instead you can create paging groups and use the loudspeaker paging feature.
Hope this helps.
Thanks