If i have public ip address on the UC500 can i use CCA to access to box?
The recommended approach is to VPN into the UC500 and run CCA over the VPN. Access directly across the Internet can work, but it requires a number of modifications to the standard firewall setup, and you may have trouble with things like uploading software updates or voice prompts for the AA if you are not careful. Managing the box over a VPN avoids all of these problems.
Use of a VPN also means you will be able to directly manage other SBCS devices behind the UC500, such as switches and wireless access points.