Ports 179, 1720 and 5060 are open to internet

We use fortigate 300c firewall and the version is 5.2 GA.

When scanned from NMAP from internet for open ports, the ports 179, 1720 and 5060 are showing open.

We use Polycom VC device for and also use VOIP too (Innodmedia).

How do we close these ports as to comply with PCI Auditing.

Please Advice