1608 IP Phones: No DHCP release sent by 16xx stations when leaving the default VLAN and booting on the Voice VLAN
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When a 16xx series phone initially boots, it receives IP address by DHCP on the default (Data) VLAN. If DHCP option 242 contains a VLAN value, it instructs the phone to boot again now on the given Voice VLAN.
Before rebooting, the phone should release the leased IP address on the default VLAN by sending DHCP release message. The fact is, the no DHCP release is sent by the 1600 series phones. It means that the IP address remains reserved by the DHCP server until the lease expires. It can lead to IP address exhaustion, i.e. there will not be enough IP addresses in the Data VLAN scope to serve all PCs and phones. The release occurs when you manually reset the phone.
