Why 3905's? Are you going to do an ACD que for your inbound calls? The 3905 is an ACD phone and consequently will function as that. You will lose console functions that you may be used to on the consoles, such as the ICI keys, Intercept, Night mode etc. Without a console your switch is in night mode all the time. Lots of function will be lost. I would see what features your operators use prior to making this change.