Hi,
First of all i would advise you to update Exchange 2010 to the latest patch level, Service Pack 2 Update Rollup 1.There are some calendar fixes in SP2 which are not directly related to your issue but as i always say, make sure you are up-to-date.
You can find the updates via Microsoft Update or via these links:
- Exchange Server 2010 SP2: http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=28190
- Exchange Server 2010 SP2 UR1:http://www.microsoft.com/download/en/details.aspx?id=28809
Have you tried to remove and re-add the mailbox to the iphone already?
Please update me on this issue and don't hesitate to ask.
Technical Consultant Exchange | MCP, MCSA, MCSE, MCTS, MCITP | Blog: http://www.reinhard-online.nl | Follow me on twitter: correinhard | Please, feel free to nominate me for MVP @ https://mvp.support.microsoft.com/gp/mvpnominate