It’s simple to configure switch port to be able to use two VLANs in context of voice and data but its bit tricky if we have to configure two data VLANs. To configure two data VLANs on single switch port we need that single switch port to be trunk. As we know trunks allows multiple VLANs to pass through it.
Configuration of two VLANs (DATA & VOICE) on Single switch port
# config t
# interface fastEthernet 1/9
# mls qos trust cos To ensures that voice traffic is identified & given priority
# switchport mode access To set switch port mode
# switchport access vlan [vlan-Id] To set VLAN as the access mode (data)
# switchport voice vlan [vlan-id] To identify VLAN as the voice VLAN
# end
Configuration of two Data VLANs on single switch port
# switchport trunk encap dot1q
# switchport mode trunk
# switchport trunk vlan allowed [vlan-id],[vlan-id]