The easy link is: http://GetComo.com easy to type in mobilephone
and the direct link is: http://mobile.microsoft.com/office/communicatormobile/default.mspx?au=manual&pc=true&sl=
source for this information: http://blogs.technet.com/brettjo/archive/2009/04/29/ocs-r2-communicator-mobile-como.aspx