Microsoft’s purchase of Skype gives it options to provide voice calling directly from it’s Office 365 cloud platform.
This article on the Microsoft site that provides an administrative template that will allow the webcam or headset Call Button to trigger Office Communicator.
A quick guide to the OCS clients available for Windows, Apple Mac, iPhone, Java phones (Nokia, Motorola) and Blackberry
There are a number of clients available for Office Communications Server OCS, including Messenger for Mac. Now WebMessenger has a solution to provide OCS access to iPhone, Blackberry, Windows Mobile, Symian and Palm