Most people buy mobile phones because they want to be able to make phone calls anywhere, anytime. All the other stuff that's crammed into phones—calculators, game players, text-messaging capability—represents incomplete solutions for problems that are better served by devices dedicated to those needs. If I want to play a game on the go, I won't buy a Nokia 8290.
Still, phones offer a lot of sophisticated functionality to support specific mobile phone needs. Users need a way to quickly change ring-tones, ring volume, and message alert tones—so phone manufacturers allow you to tweak these so that one's phone can behave appropriately as one moves from the construction site to the movie theater.
Now, the ideal solution for this problem would be a phone that could set itself—for instance, if it detected the cacophonous noise of a construction site, it could set the ring volume higher. Distinguishing between the cacophony of a real construction site and the make-believe cacophony of a celluloid construction site would need to be sorted out in the implementation phase, of course. Still, the ideal interaction between user and phone settings is no interaction.
My Nokia 8290 is three button-presses away from no interaction, which is impressive, all things considered. Nokia allows the user to create different "Profiles." Each profile has a ring volume, ring tone, message alert tone, and a keypad tone, so that you can create different sets of these for construction sites, movie theaters, cafes, board meetings, etc. I can create three settings, and toggle between them, rather than changing three things in three different places each time I go into a new environment. In fact, I can toggle between my meeting profile and my rock-and-roll show profile with 3 button-presses, by using Nokia's smart menu shortcuts.
Taking advantage of the shortcuts requires a bit of memorization, but it didn't take too much practice to learn that pressing "Menu" then "3" then "2" would take me to my customized "Meeting" profile, or that "Menu"+"3"+"1" would take me back to "Rock Show." This is a nice example of functionality that is provided to intermediate or expert users that does not get in the way of beginners.
Moreover, this shortcut functionality is built into the entire menu structure. I can start a game of Snake by hitting Menu+6+2, or access the calculator with Menu+7. I rarely use either of these, so I scroll through the menu to get at them. I do employ Menu+3+1 a lot, which consumes roughly one second each time I change settings. This is one second that I'd rather not spend thinking about my phone, but it'll do, for now.