A new white paper is just released describing walkthroughs of a solution that addresses the simple user scenario of an employee capturing information about expenses that the employee incurred while traveling. The document is only meant to teach you the fundamentals of getting devices anywhere in the world talking to Microsoft Dynamics AX.
The solution architecture described in this document lets users receive information and send transactions to Microsoft Dynamics AX 2012, even if they are not in the same domain or network as the on-premises instance of Microsoft Dynamics AX. For example, the solution lets clients access a Microsoft Dynamics AX service that is running behind a firewall. The solution has the following requirements: An Application Integration Framework (AIF) service communicates data to and from Microsoft Dynamics AX 2012. Users provide their corporate credentials in the mobile client to interact with Microsoft Dynamics AX 2012 services created for their scenarios. Only authenticated and authorized users can communicate with Microsoft Dynamics AX services by using client applications.
The paper can be found here: Developing Secure Mobile Apps for Microsoft Dynamics AX 2012