I'd argue there are several really important telephones:<p>Automatic Electric 34/40 - First one without a subset -
Western Electric 500 - First self compensating network -
Western Electric 1500/2500 - First with TouchTone -
Motorola StarTac - First Clamshell Phone -
Apple iPhone - First Modern Smartphone.<p>Out of all of these landmarks, the AE 34/40, WE 500/1500/2500 and the Motorola StarTac are the most important ones.<p>The AE 34/40 was the first what we'd identify as a modern phone in appearance, the WE 500/1500/2500, is so iconic that anyone could identify it as a telephone, it also was a huge leap forward in transmission quality, and the StarTac was the first of billions of clamshell phone, the thing most identifiable as a cell phone to anyone shown an abstract drawing.<p>I'd argue that the 500 is more iconic however than anything to come before or after it.