The article in the link above found on Mac World’s iPhone Central provides some insight into altering your iPhone’s carrier setting (ie. the ATT_US.ipcc file).

What I was originally interested in was perhaps the capability to re-enable Internet tethering since that feature became available when iPhone OS 3.0 came out and with a simple mod to your iPhone using an alternate ATT_US.ipcc file. But the tethering capability has since been disabled with iPhone OS 3.1. Yet there are iPhone users who are supposably still working on a mod.

The part of the article that caught my attention was the authors example of disabling the phones data services. Meaning turning off all non-Wi-Fi Internet access, both EDGE and 3G. Why might you want to do this? Because, as the author’s example explains – if you are in a foreign country, your carrier typically charges exorbitant rates for data network access (although buying a discount package in advance can help keep these costs down). The author’s idea of customizing your phone’s carrier setting (which can be easily undone) was to make sure you don’t inadvertently accrue any of these charges, so you’d like to turn off all data services for the duration of your trip, but still retain the ability to use your phone for calls and messages. Enabling Airplane Mode won’t do the trick, because that turns off both the phone service and the data networks. Keeping Data Roaming off (in Settings -> General -> Network) should be sufficient, but you are worried that you may inadvertently enable this. What else can you do? You can make a carrier settings change that is guaranteed to block all data network access, even when you are not in a roaming area. And, at the end of your trip, it’s easy to undo.

The solution (as I discovered after working with Dan) was to change my Wi-Fi access point on my wireless router. Basically I changed the wireless security protocol from WEP to WPA.  Apparently there are reports that show its more stable and better throughput when using the WPA over the WEP. Please note that I am also using an older D-link wireless rounter/firewall so your results may vary.

After changing over to WPA be sure to change/update any other device in your home accessing your local network via wireless connection to switch to WPA and of course changing the pass-pharse at the same time.

Also see Apple’s iPod touch and iPhone: Tips when using Wi-Fi