Segregate your networks
It is best to separate your Voice and Data devices by using different networks whenever possible. See Configuring a VLAN for information on VLAN trunking.
Create an untagged VLAN with the desired Ethernet Port and attach it to a new Voice over Internet Protocol (VoIP) VLAN.
Set up Quality of Service (QoS).
Use QoS to help avoid call quality issues resulting from delay/latency, jitter, and loss. After setting up two different networks, configure QoS. See Overview of Quality of Service.
General guidelines for latency and jitter:
Maximum One-Way Delay: 150 ms
Maximum Round Trip Delay: 300 ms
Maximum Jitter: 30 ms