The smaller the device, the more strict the requirements to optimize the interface for its specific characteristics. Some people claim that the telephone is an example of perfect usability that should be emulated by software designers. If only it were that easy in the real world. Of the three steps, only picking up the handset is truly easy . First, these numbers are actually hard to learn and remember.
International calls are even harder.
The real usability problems of the telephone show up when we do a task analysis. In most cases, you want to talk to a specific person . It would be better to be able to search a database and click on the person's name or photo to get connected, something a computer interface does well. Finding out what number to call should not be a matter of guessing where the person is, nor should you be forced to try all the alternate numbers until one works. A computerized communications system would know where the person is and what device currently is the preferred way of reaching him or her.