History of mobile phones
A cellular telephone switching plan was described by Fluhr and Nussbaum in 1973, and a cellular telephone data signaling system was described in 1977 by Hachenburg et al.
Smartphone
The first integration of data signals with telephony was conceptualized by Nikola Tesla in 1909 and pioneered by Theodore Paraskevakos beginning in 1968 with his work on transmission of electronic data through telephone lines. In 1971, while he was working with Boeing in Huntsville, Alabama, Paraskevakos demonstrated a transmitter and receiver that provided additional ways to communicate with remote equipment. This formed the original basis for what is now known as caller ID. The first caller ID equipment was installed at Peoples' Telephone Company in Leesburg, Alabama and was demonstrated to several telephone companies. The original and historic working models are still in the possession of Paraskevakos.