Are they all consecutive extensions? Maybe use BAT and export the current extensions of 20xx into a CSV file. Then, using Microsoft Excel, change the 2000 entries into 2200 by doing a "Fill Series" copy of the directory number cells to make each row the next consecutive extension. You may have to do some fine tweaking, then import the CSV back into CM using BAT.
I haven't tried this exact scenario, but give it a shot. Just make sure you have a backup of the CM database before you do any type of work with BAT.
One thing to pay close attention to is the phone models, button templates, and user associations. For instance if most of your phones are 7940's with 2 lines, no problems you just create the phone template in BAT and associate the import file to this template. The Issue pops up when you have multiple phone models, a few 7912's, some 7940's 7960's etc and different line button templates within each model. Either way it will be quicker that do it manually it's just a matter of how much tweaking you need to do.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.