Microsoft are readying Office 365, the new version of their Online Services offering, to be released within the next 3-4 months and one of the new features over it’s previous iteration, BPOS, is the inclusion of VoIP (Voice over IP) Audio.
However, due to certain licensing restrictions, it isn’t currently available in all countries that can use the Office 365 service. Below is a table showing the current standing for VOIP availability across the range of countries who have the beta.
I assume this is down to specific country laws as to what services you can provide before you’re classed as a Telecommunications Provider…surely an area MS don’t want to get into!
I have to say I’m surprised it will be available in the UK 
Cloudy with a chance of Licensing 
Where did you get this info?