Check TFTP Settings
You can determine the IP address of the TFTP server used by the phone by pressing Settings, choosing Network Configuration > IPv4 and scrolling to the TFTP Server 1 option.
If you have assigned a static IP address to the phone, you must manually enter a setting for the TFTP Server 1 option. See Network Configuration Menu.
If you are using DHCP, the phone obtains the address for the TFTP server from the DHCP server. Check the IP address configured in Option 150.
You can also enable the phone to use an alternate TFTP server. Such a setting is particularly useful if the phone was recently moved from one location to another. See Network Configuration Menu for instructions.