What is "2.5G" wireless technology? How does it relate to J2ME?

Cellular phone technologies have evolved in several major phases, denoted by "Generations", or "G" for short.

"2.5G" is an acronym which represents various technology upgrades for existing second generation cellular networks.

2.5G upgrade technologies are designed to be overlayed on top of 2G networks with minimal additional infrastructure. 2.5G technologies are packet based (as opposed to 2G technologies' circuit based, voice centric approach), and as such allow "always on" connectivity (no modem connection delays).

One of the most widely discussed and important 2.5G technologies is GPRS, designed to be layered on top of existing 2G GSM networks. Please visit the related FAQ entries on 1G, 2G, and 3G technologies for more information on the history and future of cellular technology.