openfire federation with lync server

Hi Guys,

In my organistation alredy having lync communicator,more then user in windows some of the few user in linux so i have configure openfire server with AD login is fine problem is linux spark user need to communicate with lync user  its posible ? with sigle domain ?

I found some of community same domain is not posible !! any other option please all the spark user need to communicate with lync

Thanks

chinnappan