No VLANs that involve the phones (we have VLANs for other stuff, but they are not on the phones ports), nothing special going on other than two different subnets.
Old location: 10.10.10.0/24 (Native VLAN)
New location: 10.10.11.0/24 (Native VLAN)
Cisco 890 series routers providing hardware VPN connection over 100M Down/30M up cable modem connection at each end (this is just across town, same ISP).
DHCP for IP address and basic network connection information, not using option 43/125, phones statically assigned ICP and TFTP server.
Phone is connecting, momentarily, long enough for the keys to come up, then just sits with "10.10.10.30" (the 5000's IP address) in the display for a bit with all keys showing on phone, then it reboots.
Note this is not a production system, this is my demo/test system... they just moved all the techs to a new office and left our servers and demo hardware in the old office.
I just want my phone on the 5000 to work to assist customers by walking through stuff, if all else fails I can move it to the public port and change the extension to NAT, but would rather do it this way if possible.