Digital cell phones a.k.a. "smartphones" are useful Internet client devices. If connected to your computer properly, they can also function as a general-purpose network modem. Using your cell phone as a modem provides a way to get portable Internet connectivity when all other options like Wi-Fi hotspots fail. Unfortunately, the performance of these cellular network connections may not meet a person's needs.
The theoretical maximum network data transfer rate supported by a cell phone modem varies depending on the communication standards your phone service supports.
Performance Across Generations of Cellular Technology
Modern cell network technologies fall under the "3G", "3.5G" or "4G" classifications. These include LTE, HSPA, EV-DO, and EDGE. 3G technologies offer roughly between 0.5 Mbps and 4 Mbps for downloads. 3.5G and 4G offer up to 10 Mbps for downloads.
In contrast, older cell technologies like GPRS, CDMA, and GSM offer lower speeds around 100 Kbps or lower, similar to the performance of an analog dial-up Internet modem.
The performance of cell connections varies significantly across service providers, geographic locations, and load (number of active subscribers) at a given location. For these reasons, average or peak network speeds often do not apply.
Theoretical vs. Actual Cell Modem Performance
As with many networking standards, users of cell phone modems should not expect to achieve this theoretical maximum in practice. The actual bandwidth you will enjoy depends on several factors:Quality of the phone's wireless signal (typically, the distance away from the nearest cell tower)Competing network traffic on the cell phone provider networkVersion of the network communication protocol employed by the provider, along with any technical limitations or extensions they implementMix of upstream and downstream traffic you generate (cell phone modems support less bandwidth for uploads than for downloads)
Consider that the "speed" of any network depends not only on the amount of supported bandwidth but also on its latency. A cell phone modem suffers from very high latency given the nature of its open-air communications. When using your cell phone as a modem, you should expect to see sluggish delays and bursts of data transmission, that lower the perceived speed of your connection even further.