We've got 7931 Ip phones which release their DHCP for voice VLAN and start getting addresses from access VLAN. Other types of phones work fine. I've configured SPAN to track the packets coming from the phone, and I see that IP phone starts sending DHCP requests all of a sudden.
As far as know, IP phones receive voice vlan information through CDP, may be it has anything to do with CDP exchange between the phone and the switch.
Thank you in advance!