The UC500 is connected via the Expansion port to a Linksys PoE switch (SRW248G4P). The UC500 is the DHCP server for voice VLAN 100, and a separate Windows server is the DHCP server for the VLAN 1 (native data). Here is the Expansion Port configuration:
switchport mode trunk
This port is connected to port 48 on the Linksys switch which is configured as a Trunk as well.
Ports 1-47 are configured as: (all 524sg phones are plugged into these ports)
VLAN 1: Untagged
VLAN 100: Tagged
The 524sg phones are getting their IP configuration from the Windows DHCP server on VLAN 1, so when a computer is connected to the PC port on the phone, the PC does not get an IP address and cannot access the data network.