You can test your iPhone signal strength and antenna reception easily again, it requires the iOS 4.1 update or later, but will work on any iPhone 3G, 3GS, 4, 4S, or later. Here’s how:
- Activate the antenna strength test by dialing the following: *3001#12345#*
- Hit Call
You’ll then see the signal bars be replaced with a number, the more negative the number, the worse the reception (-107 is worse than -80 for example). If you tap the numbers you can switch back and forth to the reception numbers and signal bars. You can exit out of this Field Test mode by just hitting the home button at any time.
The dialed number is actually the same field test that worked on the original iPhone 2G, but the ability was lost between several iPhone OS updates.
The whole iPhone 4 antenna fiasco is mostly a nonissue these days, but it’s still interesting to see the iPhones reception. Whether it’s right or wrong, I chalk a lot of the signal weakness up to AT&T’s network more than the iPhone itself, but this is largely due to the fact that my friends with unlocked iPhones on other networks have significantly better reception in many places.