I've had the same problem too, but it is hard to believe that Orange Tech couldn't provide you with a solution. By simply browsing through the Windows folder in the M600, I found to 2 files called Bkgnd_Port.bmp and Bkgnd_Land.bmp.
These are the background images to the Dialer Screens for portrait and landscape modes. All the number buttons and call information are superimposed over these images.
I used Total Commander to copy these files out to the My Documents folder, then, changed the brightness and contrast using XN View Pocket (but did not change the original picture dimensions). The edited files were copied back into the Windows folder to replace the original files.
I have attached zipped copies of the original and brighter images if you want to use them. Alternatively you could totally customise the images to suit your liking, but as long as you keep the original picture dimensions and file names, they should work!
Reboot the phone after you have replaced the files.
Total Commander and XN View Pocket are freeware programs and are easily found on the internet. I think the built-in File Explorer in the M600 will not allow you to tamper with files within the Windows folder. Just goes to say the you mess with these files at your own risk.
Edited by ayhansan, 11 December 2006 - 11:44 PM.