I'm testing VVX500s connected to Cisco switches configured with MAB and in multi-domain mode. MAB is authenticating successfully however DHCP fails. I manually configured the VVX500 with the Voice VLAN, and still it is not getting on the network. It has no problem getting a DHCP address from the correct VLAN when in single-host mode, nor when connected to a standard port. Is anyone aware of what could be preventing the phone from learning the Voice VLAN and actually getting onto it?