If you use a Microsoft Corporation (NASDAQ: MSFT) Windows Mobile smartphone these days, chances are its is made by Taiwan's High-Tech Computer (HTC). Newer Windows Mobile smartphone units from all major U.S. wireless carriers are made by this Taiwanese company, and millions use them daily to send and receive email, browse the web, send text messages and perform office tasks outside the office. Palm, Inc.'s (NASDAQ: PALM) Treo and the Research in Motion, Ltd. (NASDAQ: RIMM) BlackBerry are other examples of smartphones also used by business people.

Although HTC has seen quarter after quarter of rising sales in recent years, its stock has gone down on the Taipei exchange due to a bunch of new competition from competitors that don't want to see HTC continue taking all the Windows Mobile business with wireless carriers around the world. Are HTC investors worried about the Apple, Inc. (NASDAQ: AAPL) iPhone invading overseas markets soon? That's probably a little bit of the worry, as in my experience, HTC's Windows Mobile phones and Apple's iPhones are in completely different classes. Why? Because of usability.

Apple has stirred up a storm of conversation that revolves around the iPhone, even though the device is not really targeted to corporate users or business customers (at this time), and that is because it is so functional from a customer perspective that the iPhone is on another playing field. Units like the HTC Mogul, which is carried by wireless carrier Sprint Nextel Corp. (NYSE: S), have so many buttons and functions that the average business or regular consumer can be easily overwhelmed.

The iPhone? One button, and the handset operates much like a personal computer when you think about it. Most business customers and consumers know how to operate a PC, and the iPhone duplicates that in terms of user interface. Should HTC be worried about the iPhone denting its prospects in the future? Yes, just like all other manufacturers. When the second-generation iPhone begins shipping, the bar will be placed even higher. If Apple can weave in the most-requested business features into future iPhones while still keeping extreme ease-of-use, all 'smartphone' manufacturers should be worried.