When you see, hear or read about Office 365 the dialog is almost always about the broad offering we refer to as Multitenant or Shared, however there is a small group of customers deployed in our Dedicated environment. The regions currently providing voice services (PSTN Conferencing and PSTN dial-in/dial-out) are in North America (NOAM or NA) and Europe, Middle East, Africa (EMEA).
We just completed an exercise reviewing the list of supported countries in these regions as well as the Asia Pacific (APAC) region which we anticipate being available in the future. Going through this exercise I learned that there are 3 variables to consider and an interesting overlap between them.
1. We first start with a legal review of whether the voice services are even allowed in a region.
2. We calculate the distance of a country to the regional datacenter
3. We apply any United States program sanctions
The piece I found interesting was that a country could be allowed voice services legally but then removed due to U.S. sanctions.
Service Descriptions for Dedicated Subscription Plans - http://www.microsoft.com/en-us/download/details.aspx?id=18128