To get a router working you need maybe three to five settings. There are a hell of a lot more to set up a SIP registration and make it work properly - the tones alone there are twenty-odd to set.
It's not that hard, done it myself with no problems.
IMO it's all about locking a customer in, force them to buy the VF modem (or commit to a fixed term contract), so no matter how bad the service gets the customer still has to pay every month.
Best advice is to ditch the VF modem and the VF VOIP, buy your own modem and go with 2 talk, heaps of features for a very reasonable base price.
Mike has posted earlier modems should be provided free of charge and with no required resign.
You would be better off steering clear of the VF supplied modems full stop. the modify the firmware and cause so many other bugs.