We knew those little secret features would be coming today with the release of iOS4.1. Here is the first: How to enter Field Test Mode with iOS4.1
It's very simple, actually. Dial the following number exactly as you see it into your iPhone (phone must have iOS4.1): *3001#12345#*
Now hit the call icon, and you will see a new screen pop up. Field Test:
You now see a negative number. That will show you how strong your signal is. If you try the deathgrip on an iPhone 4, you will see the negative number rise. For example, -83 is better than having a -100.
Pretty cool, huh?
We did the post about different codes before - Keyed In: Lots Of iPhone Keypad Codes You Probably Weren't Aware Of
[via techmeme thanks Josh]