Existing users, 
Apple’s iPhone Signal Strength Placebo
Posted 25 September 2008 @ 8am in News
As previously noted, 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 calls. However, it appears that “more accurate” may mean “unreasonably generous.”
Noted in our previous report, 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.
iPhone Atlas reader Michael did some testing, and found that widely varying dB readings resulted in the same five-bar signal indicator on his iPhone. He writes:
“After I upgraded to 2.1, I did indeed notice a consistent indication of ‘5 bars’ of signal strength. Then I learned how to put my iPhone in field test mode so the phone displays an absolute signal strength indication of dBm rather than a relative signal strength indication of ‘bars.’ You can then tap the signal strength to switch between the two. I have done an informal survey and observed the following:
- -50 dBm = 5 signal bars
- -75 dBm = 5 signal bars
- -80 dBm = 5 signal bars
- -95 dBm = 5 signal bars
- -113 dBm = 5 signal bars
Michael’s results beg the question — does iPhone OS 2.1 really provide more accurate signal strength indication? Or does it simply inflate the signal strength reading?
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9 Comments
Posted by houdini2
25 September 2008 @ 10am
I don’t want to sound like a complete idiot, but would like to clarify (guess I’m used to sounding like a fair-enough idiot as it is!), that “a dB reading below 50 generally indicates good strength.” Is this actually -50dB? And is a reading “below” -50 considered a lower negative number? For example, does the example above from Michael mean that his reading of -113 dB is a stronger signal or is his signal of -50 dB the better signal?
I’d like to start keeping track of my phone’s performance, and am not clear if we are in the realm of negative or positive numbers. Thanks in advance for the kind assistance.
Posted by dannyt1
25 September 2008 @ 11am
I am really disappointed and pissed off at Apple for using such a cheap trick to try to convince people that they are getting a strong signal. Just fix the damn problem with reception and give us back a realistic signal strength meter, or remove it completely because it is totally useless now.
Posted by FrankMCA
25 September 2008 @ 12pm
Even if 2.1 simply inflates the signal reading, perhaps it inflates it to the same level as Nokia. If Apple was trying to be conservative in the readings, why should they suffer against Nokia and other competitors?
The same signal strength and noise level will arrive to any cell phone, so how many bars get displayed is not really helpful. It all depends on what the phone *does* with that signal.
Posted by sithel
25 September 2008 @ 12pm
My signal has drastically improved on the original iPhone after installing 2.1. After 2.0 I had been sporadically losing Edge connection and was unable at times to connect to wifi networks. This has all been cleared up.
Posted by lagreca
25 September 2008 @ 5pm
I agree with this post fully. While my iPhone does show more bars in more places, I still have reception problems. I was trying to talk to my wife today, the phone was showing full bars, but the call was garbled so badly that the phone was useless. I had to hang up, and call back later.
I don’t necessarily think this is apple’s fault, but more AT&T’s crappy 3G network.
Posted by michoffm1
26 September 2008 @ 3am
I don’t understand , as doing the same testing Michael did on my 3G gives me different results, maybe because I am in The Netherlands on T-Mobile, and not on AT&T [does this make sense?]:
-113 dBm = 1 signal bar [bad or no 3G use possible]
-52 dBm = 5 signal bars [best I got so far, 3G works perfectly]
Posted by prairiefiretexas
26 September 2008 @ 3pm
I agree with lagreca.
ATT’s 3G network sucks. Last year, I bought an ATT 3G air card for my MBP. I returned it because it was useless. The 3G coverage was weak and the card almost always defaulted to Edge. I bought a Sprint EVDO card and it rocks.
One cannot expect an iPhone 3G to be any better than the ATT network.
Posted by versiontracker2007
28 September 2008 @ 3pm
I’m getting -97, 5 bars AND very good reception and 3G speeds.
It’s bizarre how much variation there is between phones on many things, (call quality, sync issues, backup speed, lockups and errors, etc…) They all use the same hardware and same OS, why so much variation?
My wife’s phone (purchased at exactly the same time as mine) behaves differently even though they are both running the same OS version with no hacks. My phone locks up and needs to be restored upon every OS update, her’s updates without issue. Her phone won’t fall back to Edge when 3G isn’t available, mine falls back perfectly. I can get a 3G signal in places she can’t.
With Apple tightly controlling the hardware and software, you would think they would all behave the same.
Posted by caseyfitz2
27 October 2008 @ 8am
How do I turn the Field Test off? I don’t like having to tap the bar area to switch back and forth and think having this always on is draining my battery.