How does Skype works in imo.im and im+ services?

Question

How does Skype works in imo.im and im+ services? Any guesses?

I think there is only 3 ways:

1. Runing many copies of Skype client for each connecting client on server
2. Runing many copies of Runtime from SkypeKit for each client on server
3. Reverse-engineering of Skype protocol...

(Yes i know that 1 and 2 is illegal)

Has anyone any information?

Answer 1

Probably some kind of SIP-Skype hardware gateway?

http://shop.skype.com/phones/#pbx-systems lists some.

Just my guess about possible legal ways though. Reverse engineering Skype protocol does not seem to be realistic to me - those guys are very paranoid about obscurity and change their protocol details quite often.