Which aspect of early cell phone technology made the first cell phones quite expensive?

A. The limitations of the Mobile Telephone Switching Office

B. The inability of early phones to convert voice signals

C. The limited number of cell phone frequencies

D. The frequent interference from radios and air traffic control

Which aspect of early cell phone technology made the first cell phones quite expensive?

A. The limitations of the Mobile Telephone Switching Office

B. The inability of early phones to convert voice signals

C. The limited number of cell phone frequencies

D. The frequent interference from radios and air traffic control

The correct answer is:

C. The limited number of cell phone frequencies

The history of mobile phones covers mobile communication devices that connect wirelessly to the public switched telephone network.

While the transmission of speech by radio has a long history, the first devices that were wireless, mobile, and also capable of connecting to the standard telephone network are much more recent. The first such devices were barely portable compared to today's compact hand-held devices, and their use was clumsy.

Along with the process of developing a more portable technology, and a better interconnections system, drastic changes have taken place in both the networking of wireless communication and the prevalence of its use, with smartphones becoming common globally and a growing proportion of Internet access now done via mobile broadband.