Hi
Your project requirement can be full filled, if you have "Skype connect" account from Skype and Asterisk or Freeswitch as PBX, further please not that Skype connect allows user to receive call, and make outbound calls only to remote mobile or landline number ( User can't call other Skype accounts ).
I can configure Skype connect with your PBX and will also configure outbound routes as per your requirements.
Regards