The Register has a cool scoop on the history of the iPhone name, since it first appeared back in 1994:

The iPhone has been with us for many years, in a variety of forms, and its slow and painstaking development has taken many twists and turns before reaching its forthcoming destination.

Briefly: there was a band called Eyephone back in 1994; then a PC-to-PC VOIP software in 2001, then a Palm OS one in 2004, a voip service in 2004, etc..