How can Freeradius assign a VLAN ID to the device behing the IP phone

Question

I am able to authenticate the IP phone but the pc port through which the users get to the LAN do not get assigned.I observed the pc is being dropped into the same vlan as the phone.The Lan USERs are set up to authenticate withe the active directory.

Here is what i have tried

post-auth {
          if (%{User-Name}=="DCER=5C=4Chphone2X"){
                update reply {                
                        Tunnel-Private-Group-Id = "VoIP34"
                        Tunnel-Type = VLAN             
                        Tunnel-Medium-Type = IEEE-802
                       }

        }

        if (%{User-Name}=="DCER\testuser3"){
                update reply {
                        Tunnel-Private-Group-Id = "20"
                        Tunnel-Type = VLAN
                        Tunnel-Medium-Type = IEEE-802                
                }
        }

how do i edit this to allow the pc to be dropped to vlan 20 and not the voice vlan?