If you have ring.to or plan on it, there is currently an issue with trusted callers not being able to access AA when coming from a ring.to account.
The link to the bug that needs to be fixed is at: Ring.to bug to be fixed (http://bandwidth.uservoice.com/forums/252532-bugs-that-need-to-be-fixed/suggestions/6185111-trusted-callers-not-able-to-dial-into-obi-and-use)