[newbie]

I think the use of the term ISP is adding unnecessary ambiguity.

You can run a MUD from your home computer. In fact these days its easier than ever and is the perfect solution especially when becoming familiar with code-bases and general mud development and maintenance.

There are however a plethora of services out there to make the whole experience a lot less hassle and a lot less hazardous. A quick google search for will give you thousands of results.

For the more technical savvy there's the VPS route. But for any perspective MUD administrators out there. Know that getting hosting, setting up the mud and keeping it running is one of the more trivial parts of the exercise. The real work comes in building that world. That's where you'll lose the man hours.