2G vs. 3G Talk

[alra111]

Apple's new iPhone 3G S has the following talk time specifications:

Talk time:
Up to 12 hours on 2G
Up to 5 hours on 3G

Could someone explain to me briefly why the talk time is so much lower on 3G? I know data transfer is definitely better on 3G vs. 2G, but why would I want to talk on 3G is it depletes my battery so much quicker? Can I choose to talk on 2G even if 3G is available?

Thanks,

Alra111

[ElDiabloConCaca]

Because it's a more robust and faster transmission protocol/medium, and therefore, uses more energy.

Yes, you can turn off 3G under Settings > General > Network > Enable 3G.

[alra111]

Thanks a bunch, ElDiabloConCaca! That makes total sense!

It may make sense for some people to just use the phone mostly in Edge mode and switch to 3G when they need to do Internet-intensive stuff!

Too bad they don't have a setting such as:

Voice calls - Preferred mode - 3G or Edge
Data transfer - Preferred mode - 3G or Edge

That way I would always keep my voice calls on Edge and my data always on 3G.

Alra111

[ElDiabloConCaca]

You can only use one protocol/medium at a time: either 2G (EDGE) or 3G. It takes a moment or two to switch networks, so you can see that it would technically be infeasible to auto-switch to 2G for voice and 3G for data -- what if you're surfing the net with Safari and a phone call comes in? Not to mention that there are "handshaking" events that occur at the onset of a data request or a phone call initiation... and it's impossible (at the moment) for a current data/voice session occurring on the 2G network to transition seamlessly to a 3G network connection -- imagine being on a phone call in your kitchen (e.g., the 2G network) on your land line, then having to switch to the bedroom phone (e.g., the 3G network) -- but the only catch is that you have to hang up the kitchen phone before heading to the bedroom... you're stuck in a catch-22, and you'll just have to start the phone call over again from the bedroom.

AT&T is currently working on technology that would allow a phone to seamlessly transition from either a 2G or 3G network to a wifi network -- they intend to do this to relieve some of the burden on their network. That way, when a person encounters a free AT&T hotspot (like at McDonald's or wherever they are), the AT&T network can be relieved of some strain by transitioning the connection from the 2G/3G network to the AT&T wireless hotspot network mid-call -- all without having the user realize they've switched. It doesn't work as of yet, but will soon.

[fryke]

Seems to me that the iPhone often switches to 2G from 3G when you're actually receiving a call. My iPhone is on 3G when I'm at home. Like: Always. But when I get a call and talk for 3-5 minutes and then hang up, I see that it has gone 2G somewhere on the way. A couple of moments later, it returns to 3G connectivity. I'd say they have (of course!) implemented a "calls prefer 2G" feature already.