Smartphones use cell-phone network technology to send and receive data (such as phone calls, web browsing, file transfers, etc.). Developers classify this technology into generations. The first generation includes analog cell phone technology. Digital cell phones require more advanced protocols, which constitute the second generation. Between generation two and three, network engineers created protocols that are more advanced than generation two’s digital technology but not so innovative that they are a truly new generation. Developers refer to these protocols as generation 2.5. This generation includes several early smartphone protocols, some of which are still used today.
General Packet Radio Services (GPRS) is a wireless, packet-based communication service and until recently was the standard 2.5G protocol used in most smartphones. Unlike a circuit-switched voice connection, this is a packet-switched, "always on" connection that remains active as long as the phone is within range of the service. It allows smartphones to do things like run applications remotely over a network, interface with the Internet, participate in instant messenger sessions, act as a wireless modem for a computer and transmit and receive e-mails. GPRS can send and receive data at a rate of 114 kilobytes per second. Some smartphones in the United States still use this protocol, though newer, faster protocols are available.
One protocol that is faster than GPRS used in the U.S. market is Enhanced Data GSM Environment (EDGE). EDGE can transmit data at more than three times the rate of GPRS (384 Kbps). Many smartphones in the United States are now using EDGE protocol [Source: Whatis.com]. Still, these protocols are only generation 2.5. Generation three (3G) is the latest in network communication technology. Protocols in 3G transmit data in terms of megabytes per second rather than kilobytes (some as fast as 10 Mbps). While some U.S. carriers support 3G protocols, many still rely on 2.5G technology. Europe and Asia have much stronger 3G integration in their respective cell phone networks. Some 3G protocols are:
- Universal Mobile Telecommunication Service (UMTS)
- Wideband Code-Division Multiple Access (WCDMA)
- High-Speed Downlink Packet Access (HSDPA)
- Evolution Data Maximized (EVDO)
You can read more about network technologies and protocols in the article How Cell Phones Work.