Of the various "turn-key" solutions on the market, most are a computer with some of the software. They do not include the DSU/CSU or the router. Without those, how do you connect to the network?

They don't include modems. How does the customer connect to your system?

You are left to configure not only the modems, but also the modem connections to the computer. This has to be done with either multiport cards, terminal servers or communication servers. The wrong choice could severely limit the growth and capacity of your service.

Does the system include a UPS (uninterruptable power supply)? If not, your service will be down every time there is a tiny little power glitch.

Do you have the Linux and Unix skills necessary to setup, configure and administer the system? If not, does the "turn-key" system come with the necessary training?

What happens when something goes wrong (and it will) and you need help? Does that "turn-key" system come with support?

Does it come with automated backup (and verify), security checking, usage logging and the hundred other little things necessary for a full system?