I recently moved my Cisco phone VLANs from Vital QIP to MSDHCP. When the phones were on QIP, I could change the VLAN and reset the phone, and the IP would change to the IP of the new voice VLAN. Since moving to Microsoft DHCP, if I change the VLAN and reboot the phone, the phone is holding on to the old address from the old VLAN and the only way to drop the IP is to reset the configuration on the phone, unplug the phone, delete the lease, and bring the phone back up. Anyone have any insight on this? I am trying to figure out if this is a phone issue where it is not releasing the old IP or if this is a DHCP issue. If this is a DHCP issue, has anyone else run into this?
Do you have option 150 in dhcp server ?
Note, it's is recommended to run dhcp for phones on a router or switch, to eliminate dependencies from other systems.