The above is not an exact replica of Sony Ericsson’s W800i. Designing consumer electronics like mobile phones is another capability of Autodesk Inventor. This is where surfacing comes to the rescue. A feature that can be used to ease your task in designing such is the Replace Face tool. Using such tool would allow you to only create first an extrusion of a rectangular block, then draw a surface then use the Replace Face tool. When you say Replace Face, it means that your replacing an existing face of a solid with the ones like that of the surface that you have selected.
Tools such as 3D Chamfer and 3D fillet will also come in handy with regards to designing consumer electronics. The above images are rendered images of the Sony Ericsson W800i assembly. It was rendered using Autodesk Inventor Studio using a perspective camera and with reflections and shadows turned on. The design was not purely based on measurements but by approximation. I just based the model on the images of Sony Ericsson W800i that I’ve found through the Internet.