The easiest path is to experiment with mobile CRM is to download the free Microsoft for your device.
Today, Microsoft offers its own official, supported mobile clients for iPhone, iPad, Android, and Windows Phone. Microsoft has made all its apps look similar to the web experience on Windows 8.
The second option is to buy a third party mobile client for Dynamics CRM. such as Resco or CWR Mobility. Third party providers have offered mobile clients longer than Microsoft. In some ways, they are more fully featured and offer the ability to customize in ways that are not supported by Microsoft. Resco, for instance, offers the Woodford solution which is installed in Dynamics CRM to allow CRM administrators to configure the mobile experience from within Dynamics CRM.
The most expensive and difficult option is to write a custom mobile app for Dynamics CRM. You must choose a development platform and language and design the app from the ground up. You could choose a native development tool or use a cross-platform development tool such as Appcelerator or Xamarin.
The advantage of a custom app is that you can optimize the user experience. You can make your iOS app look and feel exactly like an iOS app and follow the conventions of the platform. You can have each app take advantage of the unique form factor and features of the mobile hardware. You can optimize a user experience for a task, reducing menus and navigation to the bare minimum. For instance, a delivery driver or airline gate agent might need a closely tailored user experience for enhanced speed and accuracy. The following is a screen from the InfoStrat mobile Constituent Manager solution for Android. It allows the user to identify a point on the map using their GPS coordinates.
One important consideration is where you have deployed your Dynamics CRM solution. Some apps only work with Dynamics CRM Online, and others only work with on premise deployments. For Microsoft mobile apps, you must configure your Dynamics CRM deployment to be Internet-facing. Here is a list of troubleshooting hints for mobile and IFD.