Internal Dial Plan Part 1: Configuring Extensions on Lines

I have multiple sites with overlapping extensions. Some sites use 4-digit and others 5-digit dialing. How can I build an internal dial plan so that my numbering is simple and intuitive and users can useabbreviated dialing at their sites. This whiteboard drawing is the first in a series presenting a simple and intuitive approach for building an internal dial plan that meets those requirements. this first drawing presents the simplest approach, but beware, there are problems with this strategy. Simplest isn't always the best. You'll have to watch Part 2 to see the whole story. .