Background Image on Gen 2 and Gen 3 Cisco IP phones can be changed by using the following procedure.
I will be showing you how to do for a Cisco 7965 IP phone but the same procedure can be used for other IP phones (like 7941. 7961, 7945 etc). The only difference between different family of phones will be the Image sizes.
1) Resize the Images as per 7965 Phone.
2) Full size image— 320 pixels (width) X 212 pixels (height) and the thumbnail image— 80 pixels (width) X 53 pixels (height).
3) Save the full size file as ‘large.png’ and the thumbnail as ‘small.png’ – (you can give any name as long as it match exactly in List.xml)
4) Create a notepad file called “List.xml” – do change the extension to .xml.
5) Add the following lines in List.xml
6) Save the file and double click it to open it, the file should open in a web browser
7) Load the Image files and List.xml on CUCUM TFTP
Go to the phones > settings > user settings > Background Image and select the image from there.
The information about customization can be accessed from Cisco Support link.