Does iOS 4.0.1 make a difference?

Last Thursday, just before Apple called a press conference to address concerns with the iPhone 4's antenna, the company issued its promised 4.0.1 software update. The release didn't offer new features, and it didn't change anything about the controversial antenna, but it did alter how bars are displayed on the handset's signal meter. CNET has spent the last few days testing the update to determine what it means for you. But before we get to our findings, a bit of background is necessary.

The back story
Apple first promised the update on July 2, 2010, in response to reports from users and reviewers (CNET included) that the iPhone 4 was dropping bars when people covered a gap in the phone's antenna with their hands. In a statement, Apple said it was "stunned" to learn the bar drop was caused by an incorrect display of the phone's true signal strength.

Due to this incorrect formula, users in low reception areas were mistakenly seeing an additional two bars of reception. "Users observing a drop of several bars...are most likely in an area with very weak signal strength, but they don't know it because we are erroneously displaying 4 or 5 bars," the company said. Apple then promised that the forthcoming update would adopt AT&T's recently recommended formula to more accurately display the signal strength, and would enlarge the first three bars to make them easier to see.

Making sense of it all
After the release went out, we heard from many CNET users who were confused about how iOS 4.0.1 would change their user experience. And to be honest, we didn't know what to expect when we first got it either. So to find out how the update affects everyday usability, we took two iPhone 4s--one had the update and one did not--and compared the number of displayed bars in 10 places in San Francisco. We chose three locations with historically Average reception (two to three bars using the old standard), three places with poor reception (no coverage to two bars), one place with good reception (no more than four bars) and three locations with Excellent service (a full five bars).

In four of the ten locations tested, the unaltered iPhone 4 displayed more bars than its updated sibling. In four other places, however, we saw no difference. And most interestingly, in two of the three locations with the poorest reception, the updated iPhone displayed more bars than the handset without the update.

How we did it
To conduct the tests, we held the handsets in identical positions in the chosen locations and took screenshots at the same time to record our observations. We also tried (up to three times) to place a call. To exclude any interference from attenuation or the "death grip," we made sure not not to cover the antenna gap.

Though the number of bars isn't the best measure of true reception--Apple still hasn't told us why it removed the Field test App--we used bars in this comparison because the update was specifically designed to change them. Also, the signal strength meter is the measure on which users rely most. We understand that other variables may be affecting reception, and that even two phones with the update can show a different number of bars simultaneously, but we wanted to discover if iOS 4.0.1 did what it promised.

Editors' note: In all screenshot images, the updated iPhone 4's signal meter is above that of the handset without the update.

Location 1

Where: Intersection in Financial District during afternoon commute
Typical reception: Excellent
Updated iPhone 4: 5 bars
Unaltered iPhone 4: 5 bars
Could we make a call? Yes for both phones

Location 2

Where: CNET's offices in South of Market neighborhood
Typical reception: Excellent
Updated iPhone 4: 5 bars
Unaltered iPhone 4: 5 bars
Could we make a call? Yes on both phones

Location 3

Where: Intersection in South of Market neighborhood
Typical reception: Excellent
Updated iPhone 4: 5 bars
Unaltered iPhone 4: 5 bars
Could we make a call? Yes on both phones

Location 4

Where: Basement level of restaurant in Mission District
Typical reception: Good
Updated iPhone 4: 3 bars
Unaltered iPhone 4: 4 bars
Could we make a call? Yes for both phones

Location 5

Where: Platform in Montgomery Street transit station (two levels down)
Typical reception: Average
Updated iPhone 4: 3 bars
Unaltered iPhone 4: 4 bars
Could we make a call? Only on the updated handset. Also, the other handset didn't show 3G coverage.

Location 6

Where: Interior room of a shopping center on Market Street
Typical reception: Average
Updated iPhone 4: 2 bars
Unaltered iPhone 4: 4 bars
Could we make a call? Yes for both phones

Location 7

Where: Kent's kitchen in Hayes Valley neighborhood
Typical reception: Average
Updated iPhone 4: 2 bars
Unaltered iPhone 4: 4 bars
Could we make a call? Yes for both phones (but audio was scratchy)

Location 8

Where: Ground level of parking garage in Civic Center neighborhood
Typical reception: Poor
Updated iPhone 4: 2 bars
Unaltered iPhone 4: 1 bar
Could we make a call? No

Location 9

Where: Residential street in Twin Peaks neighborhood (in our experience, an AT&T dead zone)
Typical reception: Poor
Updated iPhone 4: 2 bars
Unaltered iPhone 4: 2 bars
Could we make a call?: No

Location 10

Where: Underground tunnel in subway car
Typical reception: Poor
Updated iPhone 4: 1 bar
Unaltered iPhone 4: None
Could we make a call? No, and the unaltered iPhone dropped and regained the signal faster in between stations

Wrapping it up
After these initial tests, iOS 4.0.1 appears to have made a difference only at the middle ranges. In the four Average or Good areas, the iPhone with the update showed fewer bars than the iPhone without the update. In contrast, in the three places with Excellent reception, we saw no difference in the number of bars shown. And in the three areas where coverage is typically very weak or non-existent, we either saw no difference or the updated iPhone showed more bars.

So what does it mean for you?
Despite the bar differences, we haven't noticed much difference in real-world usability so far. Even in areas where the handsets displayed a different number of bars, we were able to place calls most of the time. Similarly, we could not place calls on either device in the worst areas. It was only in one Average place, where we could place a call on only one of the phones.

We'll continue to test the handsets in more locations over the next few days and we'll make sure to visit more rural areas outside of San Francisco proper. And in the meantime, if you have any suggestions for troublesome AT&T areas we should visit, please let me know.