I just have some comments regarding data usage on the iPhone.
It have an iPhone 3G, operating on a prepay sim. I can easily alter the apn to access the internet, via 3G (or GPRS). Now the iPhone has a data usage meter (settings, general). I notice that many apps will use a bit of data, thus activating data usage for the day. This data can come from things like ads in the apps. I was wondering, does the GPS use data? From what I can tell, using it will access the internet, if able (and if you have the apn set to on, it will load a few kb). This is annoying, as even basic apps which don't access the internet can sometime access the location services, which appears to use a bit of data.
Of course, I can solve my issues in a number of ways:.
1) close location services - but I don't want to have to go turn things on just to use them.
2) keep the default apn set to not access data - again, I don't want to have to go change it every time I DO want to go online via 3G, but I may not have a choice - I don't particularly want to have my phone access the internet and charging me for things when I don't need to.
Another question - if I choose to close off the apn so I don't access data, is there any reason to leave 3G on? Does ONLY the data use 3G? What about voice calls? What is the advantage of 3G if you don't use data?
I was just curious about exact usage of data on the iphone - when it tries to access and when it doesn't, particularly in relation to gps. Obviously apps like safari, maps, weather etc. will use data.
Your comments on data usage for the iPhone?