iPhone 3G in Action
It's up to the 3G's namesake 3G and 802.11b/g radios to keep the device tethered to the cloud, and the radio duo performs this task fairly well, even if AT&T's spotty 3G network coverage means frequent fallbacks to the slower EDGE (Enhanced Data for Global Evolution) technology. During my tests of the iPhone 3G from various locations in and around eWEEK's San Francisco offices, I clocked transfer rates of between 90K and 164K bps in EDGE mode, and between 300K and 747K bps in 3G mode. I also recorded a significant improvement in latency between the EDGE and 3G modes, with an average ping response of 476 milliseconds on the 3G link, compared with 779 ms on EDGE. I conducted my tests with DSL Reports' iPhone-optimized Web test tool.
There have been reports of voice call drops and related unreliability with the iPhone 3G, but in my tests of the 3G, I've found its voice performance was unremarkable. As I moved through the city, I would sometimes encounter holes in coverage, and could see the iPhone move between its 3G and EDGE modes, but the experience was similar to that with other cellular handsets I've tested.