Tuan is a network administrator for a large organization. The company currently has 4 T-1 lines providing Internet access at a manufacturing facility but is seeing issues with the newly deployed Voice over IP (VoIP) system. Which of the following might Tuan want to consider that will not require additional bandwidth?
a. Convert the network from RIPv2 to OSPF b. Open port 53 on the perimeter firewall c. Implement QoS d. Implement PoE