Use the Lync - Options dialog box to set up or change your phone settings.
What do you want to do?
Add or change phone numbers
To open Phones options, open Lync, click the Options button 
Phone numbers defined in your corporate directory system may be visible to all contacts in your organization who are assigned to My Colleague, Workgroup, or Friends and Family privacy relationships. They are not visible to users who have Blocked Contacts or External Contacts relationships. For more information, see Control access to your presence information.
Use a Text Telephone (TTY)
If you or a contact must use Teletype (TTY) because of a hearing impairment, a TTY device must be connected for the feature to work.
To connect a TTY device, view Phones options, and then select the Turn on TTY mode check box.
Specify a conference call phone
By default, the conference call number is set to Lync Voice over Internet Protocol (VoIP). If your work number is listed as one of your phone numbers, you can specify which one you want to use in conference calls or online meetings.
To change it, view Phones options, and then select a phone from the Join meeting audio from list.
You can also select whether to be prompted to select a device each time you join a meeting.
