What Format should you choose

Who are your visitors?

First, get to know who your website visitors are.  Knowing their Profession, Title, Revenue, Age group and Gender will help to determine what kind of device they are using.  For instance, young Executives are the most inclined to use PDA phone.

If you have an existing website, check your reporting tool and find out how many visitors came from Mobile Devices by looking at the statistic regarding the type of Browser used.

What do you need to show your visitors?

The next step is to understand your requirements.  Will you need to display pictures or graphics?  Do you require a streaming technology for movies or music?  Can you get away with Text only?

These questions will help you define your options.  If you need to have some streaming media, then Pocket PC should be your choice.  If Text is enough, then a Cell Phone format would work just fine.

The smaller format the better

Once you have your options defined, keep in mind that if you choose to have only one Mobile Device Format, the smaller the better.  A website formatted for a cell phone (the smallest screen size) will work just fine for bigger devices like Pocket PC or Smartphones.