Useful post on the Microsoft Volume Licensing Blog covering dual access rights with Office 365. Three key takeaways:
- There’s a good table showing which plans equate to which CALs (note that not all Office 365 plans include dual access rights)
- Underlying on-premise servers need to be licensed for users (SQL and Windows Server to support SharePoint, for example) and
- Office 365 USLs can be used to access licensed servers deployed on third party servers (licensed via Licence Mobility). http://bit.ly/1cdivtH