Some companies also have to consider least cost routing as well in determining call cost.

CIP: Let us say, a company headquartered in Detroit, has a national company with at least 1 store in each area code in the states. And has offices in major cites in most cities across the world. With a connected Phone system to all locales the office/stores are.

Let us say that some regional executive in Colorado's Store has a problem with a machine built in Tokyo Japan, needing direct support from them. The phone system will need to know how to route the call over the companies internal phone system. Making it a local call for the store/office in Tokyo. Since the already are paying for the connectivity to Japan, it is a reduced cost for them.

Just think of doing this... and capturing the info this way. Fun Fun Fun.