I’m starting to conclude there are four ways a user will interact with a phone. These four modes or four methods are:

(1) Checking incoming messages or current device status. This should be very quick and unobtrusive: you should be able to just press a button or two and get the status you want.

(2) Sending a message. This should also be relatively quick, though often people are willing to spend time composing messages, such as SMS messages or quick e-mail messages. And in this category I’d put chatting away on the phone: you’re involved with the device communicating to someone else.

(3) Searching for something. This may wind up being involved, but ideally this should be somewhat location-based for some types of searches.

(4) Playing games. You’re sitting around for a few minutes killing time, and you want a way to pass that time.

Some things that sound like they should fall into one category really fall into another: surfing the ‘net on the iPhone, for example, strikes me as an activity similar to playing games–a way to kill time. Other activities may also sort of fall into multiple categories: for example, if you search for a movie theater to see what’s playing, is further followups to that theater a ‘search’ activity or a ‘status’ activity? (In other words, would you want to revisit the movie theater to see what’s playing on a different day, or do you want to be alerted 20 minutes before a movie at that theater starts so you remember to wander back to catch the movie?)

I think one of the mistakes people are making with respect to the phone is that they are treating it as a desktop computer, rather than as a sophisticated communications device. More than once I’ve seen people try to suggest the iPhone become an ‘immersive’ environment. How immersive can a 5″ diagonal screen be?