If the Alternate TFTP fields are blank or incorrect, the CUCM will not be able to update code or configure the device.
Begin by pressing the Applications button on the phone's keypad.
Press the keypad number corresponding to Admin Settings (6).
Press the keypad number corresponding to Network Setup (1).
Press the keypad number corresponding to Ethernet Setup (1), or Wi-Fi (2) if your phone is connected to your phone wifi network.
Press the keypad number corresponding to IPv4 Setup (1).
Enable Alternate TFTP by using the circular rocker button to navigate down to the Alternate TFTP option.
Select the Softkey to change the setting to On.
Scroll down to the TFTP Server 1 option and press the middle button of the circular rocker to change the value.
Change the value to TFTP server1 - 10.203.32.210 and TFTP server 2 - 10.203.32.200.
When finished select the Apply softkey.Select Erase when prompted that a Trust List is installed on the phone.
The phone may disconnect from the VPN and then reconnect.
NOTE: if the TFTP setting are not configurable, the Network Settings may need to be reset (Admin setting →Reset settings → Network settings).
After the reset, connection to the home network is required, before following the above steps again.