I have a couple of Cisco CP-7841 IP Phones that are working otherwise well, but the backlight controls are not working. I would like to have the backlight off unless the phone is being used (IIRC this was the default setting on older Cisco/Linksys SPA series phones).

The SEP[...].cnf.xml file is configured like this (display related settings only, other omitted):


However the settings on the phone display say (the last three do not match):

Active Load: sip78xx.14-2-1-0101-26
Backlight On Time: 08:00
Backlight On Duration: 10:00
Backlight Idle Timeout: 00:10
Days Backlight Not Active: Sunday, Saturday

I think these are the default settings, so something might be wrong with my XML file. I have checked from https://usecallmanager.nz/sepmac-cnf-xml.html that the syntax should be correct.

Any ideas? Thanks!

  • Unfortunately, questions about hosts/servers are off-topic here. You could try to ask this question on Server Fault for a business network.
    – Ron Maupin
    Commented Jul 30, 2023 at 5:31

1 Answer 1


Hmm, as soon as I posted this question, I noticed the similarities between the "display" settings and the ones applied on the phone - it seems that the "backlight" settings do nothing and the backlight is in fact controlled by the "display" settings.

For example, setting:


Results in the phone saying:

Backlight Idle Timeout: 00:03

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