Conclusion: The Motorola ES400S is for businesses with Sprint contracts, and it succeeds as a proper enterprise tool that works worldwide with legacy Windows Mobile apps. Just make sure you get the extended battery.
Pros: True world phone. Robust enterprise app support and management tools. Tough, rugged design. Loud speakerphone and push-to-talk capability.
Cons: Bulky. Sluggish. Ancient Windows Mobile OS. Background hiss during calls. Short battery life.