Looks like its just in the V81 for Yealink T46s and T48s
As a workaroung I have been placing a file y000000000066.cfg in the /usr/share/ombutel/ww/includes/xepm/provision/ directory with the following parameters that are missing from the module for the wallpaper and addon buttons
#!version:1.0.0.1
##File header “#!version:1.0.0.1” can not be edited or deleted, and must be placed in the first line.##
wallpaper_upload.url = http://10.1.1.5/xepm-provision/wallpaper.jpg
phone_setting.backgrounds = Config:wallpaper.jpg
expansion_module.1.key.1.line = 1
expansion_module.1.key.1.type = 16
expansion_module.1.key.1.value = 101
expansion_module.1.key.1.extension = **
expansion_module.1.key.1.label = Bill
expansion_module.1.key.2.line = 1
expansion_module.1.key.2.type = 16
expansion_module.1.key.2.value = 102
expansion_module.1.key.2.extension = **
expansion_module.1.key.2.label = Taylor
expansion_module.1.key.3.line = 1
expansion_module.1.key.3.type = 16
expansion_module.1.key.3.value = 103
expansion_module.1.key.3.extension = **
expansion_module.1.key.3.label = IT
expansion_module.1.key.4.line = 1
expansion_module.1.key.4.type = 16
expansion_module.1.key.4.value = 105
expansion_module.1.key.4.extension = **
expansion_module.1.key.4.label = Floral
