On the DHCP server, you will need Option 176 in BOTH the data and voice scope.
Data Scope for untagged VLAN:
Option 176: "L2Q=1,L2QVLAN=XXX" (XXX is your Vlan ID)
Voice Scope for Tagged voice VLAN:
Option 176: MCIPADD=xxx.xxx.xxx.xxx,MCIPORT=1719,TFTPSRVR=yyy.yyy.yyy.yyy,VLANTEST=0 (the xxx...