Cell phones use radio technology. The first generation of cell phones used the analog system, with a certain number of channels in each cell. However, the analog system didn’t have the technology to compress the signals that were transferred between the cell phone and the cellular network, which created system overload. A system with more capability was needed.
Digital technology uses radio technology in a different way than the analog system did. Second-generation cell phones use the digital transmission system, which increased the number of available channels and thus increased the number of calls that can be held simultaneously. This is also true for cable companies, which use the digital system to fit more channels into each bandwidth.
Digital phones use a complex conversion process to transfer your voice by compressing information. Your voice is first converted into binary information (1s and 0s), and then compressed before being transmitted. This process of compression enables more calls, up to ten digital cell phone calls, to be compressed to take up the space that one analog call does. Digital cellular systems use FSK -- frequency-shift keying -- to alternate between analog and digital, converting and sending the information back and forth between the cell tower and the cell phone.
The digital processing is powerful and quick; it retains good voice quality and gives greater service within each cell. Digital cell phone service is quicker than analog and much more efficient, which is why the analog system has become outdated so quickly and why digital systems have taken over.