Microsoft brought Windows Live Messenger and Skype together. In April 2013, Messenger users were migrated to Skype upon sign-in. Lync customers who rely on federation with Messenger will continue to be able to communicate with their Messenger contacts, even after those contacts update to Skype. There is nothing that Lync administrators or Lync end-users need to do to maintain continuity of service, and management of this capability within Lync remains the same as it has been for communications with Messenger. 

When Messenger users sign into Skype using their Microsoft accounts (i.e., the same credentials used for Messenger) all of their Messenger contacts - including federated Lync contacts - follow them into Skype. Presence sharing and instant messaging between Skype and Lync for these contacts is available. 

Lync-Skype connectivity - contact adding, presence sharing, instant messaging, and audio calling between Lync and Skype users - is also now available to all Lync customers.

Federation with Yahoo! and AOL are both on a path toward end-of-life for customers of Lync (and Office Communications Server). Microsoft’s ability to provide each of these services has been contingent upon support from Yahoo! and AOL, and the underlying agreements of these are winding down. For both Yahoo! and AOL, service will continue through June 2014.

• Yahoo - Service will continue through June 2014, and customers continue to need to be licensed with the Microsoft Lync Public IM Connectivity User Subscription License (“PIC USL”).  As of September 1st, 2012, the PIC USL, is no longer available for purchase for new or renewing agreements.  Customers with licenses purchased prior to this date will be able to continue to federate with Yahoo! until the earlier of the service shut down date or their license expiration. Read the announcement on the Lync Team Blog. Customers who have PIC licenses on agreements that extend past June 30, 2014 will receive a credit in proportion to the amount of the payments covering the time period following June 30, 2014.

• AOL - On June 30, 2014, Lync's IM connectivity ("PIC") service will no longer be available. In order to limit customer disruption when the service ends, we have discontinued the provisioning of additional customer domains. Until June 30, 2014, customers do not need to do anything to continue to support federated communications with AIM. Beyond this date (or for customers that would like to provision additional domains in the meantime), a substitute service is available directly from AOL. For more information on AOL's new service, see Establishing Direct Federation with AIM  (opens new page on AOL.com).  

The following table provides a summary of the Public IM service providers, federation capabilities with Lync, and licensing requirements.