Sometimes it is nice to be able to appear offline when you are logged in using Office Communicator. Setting for using this is when you need to be offline but appreciate being able to see presence of others in Communicator, Outlook and Sharepoint. To apply this you need to use regedit:
- You need to create following registry DWORD and set its value as 1 to enable it.
- The DWORD name is EnableAppearOffline, type is REG_DWORD and location is
- My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Communicator.
- After making above change, exit from office communicator (from system tray) and relaunch it.
msunified.net 
What if I want to do the opposite — appear to be logged in when I am actually Away or Offline…? The maximum custom setting in Communicator is 60 minutes, and then it automatically shows you as Away. What if I want to take a long lunch? ;-)
Hehe, I don’t have a registry setting for that, but let me know if you find one :)