Final answer:
The correct command to assign a voice VLAN to a switch port is 'switchport voice vlan 150', which segregates voice traffic onto VLAN 150 for QoS management.
Step-by-step explanation:
The statement that the command to assign a voice VLAN to a switch port should be switchport voice vlan 150 is true. For configuring a switch port to carry IP phone traffic, you do need to specify the VLAN that the voice traffic will use. This is done by using the switchport voice vlan interface configuration command on a network switch. By setting the VLAN to 150, you are assigning the voice traffic to VLAN 150. This helps in segregating voice traffic from data traffic and can help greatly in managing Quality of Service (QoS) for the voice traffic.