Most of the big name vendors of webinar software (WebEx, Microsoft, Raindance, etc) run the software on their own servers and as a client, you set up your little section of their world and have people link to the vendor’s domain. But there is a specialized market for webinar software that sits locally on a company's own network.
I had a chance recently to see a demo of Sonexis ConferenceManager. It was interesting to look at this alternative to buying time from the big boys. Sonexis sells you a physical piece of hardware that goes into your datacom network. It manages port connections and everything else necessary to host your own webinars without any outside networks or software. It synchs up phone connections through your in-house telephone network (PSTN) or can handle VOIP audio.
Obviously if you go this route, you have to get more of your technical people involved in the purchase, installation, and support than with a fully hosted solution. You can’t suddenly say "Hey, everybody... Let's put on a show!" You are also responsible for setting up whatever incoming phone line(s) you want to use for your audience. And the solution isn't geared for those giant mass marketing webcasts where you may have audience sizes in the many hundreds (or even thousands). It will support up to 100 seats in a single conference, with a maximum of 192 seats total for all simultaneous conferences.
But the advantages are there for certain classes of web conferencing. If you do many smaller conferences, the payback can make sense. You pay a one-time cost for the hardware and software instead of ongoing subscription fees and usage charges for a hosted solution. If you are worried about the security of your information, this keeps everything on your own system, where you can manage firewalls and the like.
As I said, the product isn't really intended for big open registration marketing events. Setting up customized registration pages requires the use of a third-party vendor. It lacks a few features I have found useful for such events – for instance, responding to attendee questions individually instead of publicly. But don't downgrade a product for not solving a problem it didn't aim at. For smaller collaborative meetings, sales presentations, and training sessions, this could be a serious contender.
Remember that Webinar Success offers vendor selection assistance, where we will look at the specific needs of your event, then evaluate and recommend vendors who can best suit your needs.