query: What year were cellphones invented?
passage: History of mobile phones
A cellular telephone switching plan was described by Fluhr and Nussbaum in 1973,[20] and a cellular telephone data signaling system was described in 1977 by Hachenburg et al.[21]
passage: Volta Laboratory and Bureau
The Photophone, also known as a radiophone, was invented jointly by Bell and his then-assistant Sumner Tainter on February 19, 1880, at Bell's 1325 'L' Street laboratory in Washington, D.C.