Lync 2010 can display presence information for contacts who use email services such as the Windows Live network of Internet services (including MSN and Hotmail), AOL®, and Yahoo!®, and who are joined to Lync. Federated users (users who are outside your company) can do activities such as share presence information, make Lync calls, and conduct video conferences.
Open Lync, and, in the search box, type the email address for the person that you want to add to your Contacts list.
In the contact card that appears, click the Add button.
Select a contact group in which to place the contact. Also, you can create a new group at this time by typing the name beside the New Group field.
Some users have an email account with a service that is not federated with Lync. Although you can add these users to your Contacts list in the same way you add federated users, you won’t see presence information for them.
Other users sign in to a federated site by using their non-federated user ID (email address). If this is the case, use the format user(unfederated.com)@federatedcompany.com--for example, MrContoso(gmail.com)@msn.com.--when you add the contact. Using this format will ensure that his or her presence will display in Lync.
For a video demonstration of how to add a contact, visit Office.Microsoft.com for Video: Add a contact. (0:32)