If you go to Google and search for 'intitle:"NBX NetSet"' , without the quotes, you turn up a few phone systems that have been indexed, some even in Michigan. This might be old news to some but still a bit surprising to me. It looks like newer versions of the 3com software automagically puts in a robots.txt entry for you.
If a new VxWorks/etc exploit comes out that affects port 80 on those call centers, I wouldn't want to be using those phones at the time. Good way to take a company offline unfortunately.
I bumped into this when I was reading up on NBX items.
Looks like a simple IGMP tunnel program but specifically tailored for NBX.
http://www.nbxmulticast.com/
I haven't tried it personally but it could be helpful for people "stuck" with partially working remote phones.