Note: The application will only work in conjunction with service from AT&T. AT&T Collaborate (tm) is a solution for IP telephony, video telephony, presence and messaging. The AT&T Collaborate app is a SIP UA client for iPhones, also supporting XMPP, connected to the Internet and the AT&T Cloud. It also has integration with an AT&T server platform for various calling features. End-users keep a contact list in the client showing the presence status of their friends, family and colleagues. From this single interface the end-users can easily initiate and receive phone calls, video calls, and instant messages.