[Freeswitch-users] calling Skype-users and receiving calls from Skype-users

Hello, i would like to know, if it's possible from FreeSWITCH to call Skype-users and to receive calls from Skype-users. As I understand, with "SipTheeSkype" that is to some extent possible. But I am not sure whether or not on the Skype client, some addtional software is required (what is not the thing i'd like) What approach would you recommend to go? Thank's a lot for any help! Bill