Thanks to everyone that responding!
Touch Tone Tommy had the closest correct answer after talking to Avaya.
During IP Office upload or send file, if a phone isn't plugged in and the extension has voice mail, then the screen shows (In Manager) a # or a hash sign to show a missing telephone.
As To way no essential edition license (EEL) is because the customer purchased the system via Internet and the selling company stated a EEL wasn't necessary. Even after I suggested they call them back and order a EEL the selling company convinced the buyer not to purchase one.
And yes, to all of you who commented about programming, Basic is okay but I personally prefer programming in the Essential Edition or above. I just don't like the Manager interface for Basic programming.
Sizbut, yes it does cause a problem until you do next upload or send file. Because when doing previous send if there isn't a phone then # sign appears in Manager on the next link. If you plug in a phone before a new upload the phone shows a #before extension number on display and doesn't work.
Sorry for the delay to everyone, this cause a lot of frustration at the last minute, when we were leaving at 11:00 PM.