Microsoft Office Communicator Mobile (2007 Release)
Microsoft Office Communicator Mobile is a unified communications client for Microsoft Office Communications Server 2007. Communicator Mobile runs on Microsoft Windows Mobile 5.0 or 6.0 software for Pocket PC and smartphone devices.
Microsoft Office Communicator Mobile (2007 Release) extends the reach of Office Communications Server 2007 to information workers who use Windows Mobile powered devices. Communicator Mobile provides presence and communication features that are similar to the desktop version of Microsoft Office Communicator 2007 when users are away from their desks.
Download here (requires Microsoft Office Communications Server 2007)