Using Lync, users can place calls by typing a name or phone number on their keyboard, or using a dial pad displayed on their screen. Users can also initiate calls directly from their Contacts list. You can also deploy Lync Phone Edition devices, which are stand-alone IP phone devices provided by Microsoft partners.

Users can have multiple phone devices registered with Lync Server, and can switch between them easily.

Users are alerted to incoming calls on all their devices simultaneously, with customizable ringtones on IP phone devices and a notification similar to an instant message on their PC.

Users can also set a single telephone number that connects to their desk phone, PC and mobile phone, so they can be reached no matter where they are.

While on a call, a user can answer additional incoming calls or initiate outgoing calls, and the existing active call is automatically put on hold. Calls can be transferred from one user to another, either directly or after the first user speaks privately with the second user. Users can also transfer calls to another device; for example, they could transfer an active call to their mobile phone as they walk out the door of their office.

When talking to another user with Lync, users can easily add text, video, or desktop sharing to the call. The Do-Not-Disturb feature is integrated with the presence settings in Lync.

With Exchange Unified Messaging (UM), Lync and Lync Server integrate with Microsoft Exchange Server 2013 and Microsoft Outlook 2013. Users can see if they have new voice mail both in their Lync window and in email. While in email they can click to play the voice mail audio in an email message, or view a transcript of the voice mail message.

Enterprise Voice includes several advanced calling features as well, such as delegation, team calling, Group Call Pickup, and Response Groups.

Delegation enables users to delegate call handling to one or more assistants. The delegate can perform multiple calling tasks on behalf of the user, including screening calls, placing calls, and initiating conferences.

Team calling enables a user to have incoming calls simultaneously ring the phones of teammates so that anyone on the team can answer the call.

Group Call Pickup, a new feature in Cumulative Updates for Lync Server 2013: February 2013, lets users answer incoming calls to their colleagues from their own phones. Group Call Pickup differs from team calling primarily in that an incoming call rings only at the intended recipient's phone, but any other user can choose to answer it by dialing a call pickup group number.

Response Groups can be set up for queuing and intelligently routing calls to designated agents. Common uses include IT helpdesks, human resources hotlines, and other internal contact centers.

Lync Server uses standards and published interfaces to interoperate with existing infrastructure. It supports both gateway and SIP options (such as SIP trunking) for interconnection to IP PBX systems and the PSTN networks, so that you can migrate users to Enterprise Voice over time, while minimizing disruption. Lync Server supports traditional codecs such as G.711, G.722, and G.723.1 for interoperability with traditional VoIP solutions.

With call admission control (CAC), administrators can set limits on the amount of Lync Server voice and video traffic carried on constrained network links, and specify the action to be taken if a new call would exceed the limit. The actions could include routing by an alternate path, or refusing the call.

Lync Server works with third-party Survivable Branch Appliances to provide local calling services and connection to PSTN at branch offices, in case of WAN failure at the central site.