Administrator's Manual 47. Recovering Firmware
Version 2.2.8 257 400HD Series IP Phones
47 Recovering Firmware
This section shows how to recover the phone's firmware. See also Appendix C for more
detailed information. If the phone is powered off for some reason during the firmware
upgrade process, the phone becomes unusable. The recovery process is also available
when the phone is connected to a VLAN.
To recover the phone firmware:
1. Ensure that your DHCP server supports Options 66 (TFTP server address) and 67
(firmware file), and that these are configurable.
2. Before connecting the phone, verify that the TFTP server is running and the firmware
file for recovery is located in the correct location.
3. Connect your phone to the IP network, and then connect the phone to the power outlet;
a. The phone sends a TFTP request to the IP address indicated in the DHCP Option
66 field to retrieve the firmware file indicated in the DHCP Option 67 field.
b. The phone, in the DHCP Discover message sends its model name in the DHCP
Option 77 field. The DHCP server, according to the phone model, sets the
appropriate firmware file name in the DHCP Option 67 field sent to the phone
(e.g., 440HD_2.2.2.img).
c. The phone then upgrades to the recovery firmware.
d. After the firmware upgrade process completes, the phone boots up successfully.
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