Yes, Lync provides you with audio and video calling, web conferencing and internet chat (or internet messaging (IM).
Lync is fully integrated with Microsoft Exchange so you can see and manage all your contacts easily. It also offers presence management – so you can indicate to your contacts whether you are busy/available/offline, helping to reduce ‘telephone tennis’.
Up to 250 participants
No, anyone can attend all they need is access to the internet
Yes, There is a Lync app for Windows Phone, iPhone, iPad and Android
Yes they are stored in a conversation history folder within Outlook for easy reference