Hi Peter, thanks for your answer
We actually come from the classic method before deploy voice-vlan command, where we had:
* manually enabled the voice vlan tag on the interface
* manually enabled the voice vlan tag on the IP phone (since our 3COM 3500 IP phones don't support lldp-med)
Surprisingly voice-vlan command worked just fine for our IP phones since we left the classic method.
It is the other (native and 802.1Q) vlans' hosts that misbehaves until I disable voice-vlan command.
Still looking forward to hear other experiences and advices before start un-deploying voice-vlan command.
Regards.