Users continue to report poor 3G signal strength under iPhone OS 2.1. To be clear, iPhone OS 2.1 does not purport to actually boost signal strength. Instead, it provides "more accurate" signal strength display, which, in most cases, means more bar bars, but not necessarily better reception or ability to make/receive cals.
Two sample reports from this Apple Discussion thread:
- "the point is that the 3G did go from zero to all the bars but still dropping the calls!
- "I just bought my iphone yesterday and asoon as i got home the reception was terribal so i updated it to 2.1 and instead of getting no bars i get 1 to 3 bars but it goes off and on and turns 3g off and goes to edge."
The most reliable indicator of actual signal strength is the iPhones dB meter, which can be accessed in field test mode. Dial *3001#12345#* then press "Call." A dB reading below 50 generally indicates good strength.