You can set the Layer 2 priority on a softphone (or physical phone) using IEEE-802.1p bits in the IEEE-802.1Q VLAN tag. This is useful if the telephone and the attached personal computer are on the same VLAN (same IP subnetwork), but the telephone traffic requires higher priority (Trunking for softphones or physical phones). Enable 802.1Q tagging on the IP phone, set the priorities as desired, and set the VID to zero. As per the IEEE standard, a VID of zero assigns the Ethernet frame to the port VLAN or the native VLAN.

Cisco switches function differently in this scenario, depending on the hardware platforms and OS versions.