More often than not, our customers have mutliple DID, sometimes up to 100 per customer. We have been discussing ways to improve the setup process.
A simple addition that would help a lot for setting up the inbound routes would be a "Create and New" button when creating routes. This would essentially create the current record, but stay on the screen allowing the user to create a new route without going back to the route list.
Other systems we have take this idea a step further and have a Save and Clone feature which will give you a new record based on the current entry (which is also very helpful).
BTW, has anyone else reported or experienced the really slow load time on the create route page? Getting to the buttons at the bottom of the screen seem to take an extra 10 seconds.