i am new comer here, and new end user of polycom. i already bought Polycom HDX7000 HD for 2 units. I will place 1 unit in fix place, let say in central office. And the other one will be used in many places alternatingly, such in place A on monday, moved to place B on tuesday, then moved to place C on wednesday. Can i only have fix public IP internet in those four places, or i need to have VPN for those four places?