Force background image to Cisco IP Phones

I have tested this on a 7971G and seems to work just fine.

1) Set the ssh username and password on your phones via callmanager:
https://supportforums.cisco.com/docs/DOC-13692

2) Log into your ip phone
ssh ipaddressofyourphone

3) tftp the image you want from callmanager to your phone:

tftp -s 192.168.1.10 Desktops/320x212x12/yourimage.png /flash0/Desktop

Where "192.168.1.10" represents your tftp server
"Desktops/320x196x4/yourimage.png" is the path to the file. Keep in mind
that different models have different default tftp paths and image formats.
Google your model number and "background image" and you will find the
admin guide for your phone and all that is needed.

Also note that most simple linux commands work, in terms of navigating the
filesystem and cat'ing files etc. I suppose you could push a ringtone here
as well.