Anyone having issues with the screen contrast on Mitel 5340 phones? Suddenly a lot of our phones are having issues where the contrast changes, in some cases to the point where the screen is unreadable.

Does the contrast adjustment have any effect on the screen one way or another?

It does...and I know like a year after we first installed the system many of them had to be adjusted, but now I'm suddenly seeing a lot of them where its getting extreme - you correct it, and then a few days later is either lighter or darker again.

I think I see the problem, although I'm not sure what's causing it. As far as I know the volume adjustment is supposed to adjust ringer volume up or down when the phone is idle - well right now its adjusting contrast. Someone went to turn up the volume and the screen went black. Figure that one out!

Just looked at the manual, I guess thats normal operation. Not sure why the screen contrast is easily changable yet the ringer takes programming a button to change.

the ringer can be adjusted while it's ringing , handset volume when off hook on the handset and handsfree speaker volume when handsfree