You’ll find it in the Marketplace – or here:
Still – the wording is unclear. Will I be able to make SIP Calls? Well – only one way to find out – I am installing my Windows Phone right now.
I saw the Lync client for a few seconds in the marketplace - then Windows Phone realized my Live Account is somehow bound to a non US location. Lync is now gone. Trying a different account next.
I was able to install Lync but unfortunately somehow the setup of our infrastructure is not complete yet - should have worked, but the external discovery address is not reachable (as I said - it should work, so this will be some interesting troubleshooting).