gr8whtd0pe,
Let me put it this way so hopefully there is no confusion.
IF you have a PEC [Processor Expansion Card] AND you are using remote IP phones then you have to have a Public IP addresss pointed to the PEC that is different than the one pointed to the Base Processor, otherwise you will have audio issues. The IP Phones will never use the Public IP address of the PEC as their Controller IP, it is always the IP of the Base Controller.
So, to answer your question yes you have to have NAT to point to the two different Public IP Addresses of the Controller if there is a PEC installed on the Base Processor, but you cannot point IP Phones to that public IP address and expect it to work properly.
Thanks,
TE