Jabber is a software-based device that mimics a desk phone by presenting a phone interface on the computer or smartphone, complete with a dial pad and call handling features (such as Mute, Hold, and Transfer). 

With Jabber, you can bring your Brown phone number with you, even if you're away from your desk! Jabber is a unified communications application for Windows, Mac OS X, and mobile devices. It'll let you make and receive phone calls*, conduct encrypted chats to others who are logged into the system, and search the Brown directory.