Verizon iPhone 4: Thoroughly Reviewed
by Brian Klug on February 13, 2011 9:32 AM ESTVoice Quality
The other side of things is voice quality. Unfortunately we're still working on devising some objective call quality tests. On paper, the AT&T iPhone 4 supports wideband and narrowband adaptive multirate (NB-AMR and WB-AMR) voice codecs (vocoders) on UMTS. Remember that on UMTS (3G) voice and data are multiplexed and work at the same time. There's more bandwidth on that link, and as a result UMTS has a higher bitrate voice coder than GSM. That said AMR is variable bitrate (hence the name) and changes depending on link quality. UMTS has more dynamic range compared to GSM and CDMA2000 (EVRC) voice.
On the Verizon iPhone, EVRC is used as the vocoder. That's pretty much standard fare for CDMA2000 voice. The CDMA2000 spec has a number of different of vocoders, the most popular of which are 13k (for 13 kilobits/s), EVRC (which is 8, 4, or 0.8 kilobits/s), and somewhat newer EVRC-B. Way back in the day, it used to be almost trivially easy to change vocoders on Windows Mobile devices, and 13k sounded noticeably better than EVRC, which uses more compression. I've always found EVRC to be noticeably less appealing from an audio perspective than UMTS voice (WB-AMR), but roughly comparable to GSM voice. With EVRC there are audible compression artifacts at the start and end of spoken words, and more blocking and drop-out when 1x signal fades. In comparison, UMTS voice only drops out and degrades substantially right as you're at the bleeding edge of dropping the call entirely. EVRC has less dynamic range than UMTS, so it sounds subjectively louder - the tradeoff is that you lose high and low frequencies. Listening to "ess" sounds in words while on calls is always where the difference is noticeable.
The difference in dynamic range translates to the Verizon iPhone 4 being much louder, the same effect we discussed with the original iPhone 4 between calls on GSM and UMTS.
I set out to show the difference between GSM, UMTS, and CDMA2000 voice by calling the local ASOS weather station. I put together a video with the two iPhones calling the same number and running through the weather report one complete time. Unfortunately, the video camera I have doesn't quite do justice to how audibly different the three calls are, and I lack high quality audio recording equipment. We might follow up with different audio equipment soon, however.
The bigger difference between the two is reliability. Because voice and SMS goes over 1xRTT on Verizon, usually when you can't transact data, calls still work. With the AT&T iPhone 4, when saturation on UMTS happens, you won't be able to call or transact data unless you manually toggle 2G. The result is some built-in robustness for voice on Verizon purely because of that voice/data segregation. In addition, Verizon often puts 1x voice on 800 MHz spectrum and EVDO on 1900 MHz PCS where posisble, so voice coverage tends to work even in places data doesn't necessarily.
In use, the Verizon iPhone 4 will briefly show the "o" symbol for 1xRTT data and then quickly re-acquire EVDO and show "3G." After a call you can see this behavior and the quick re-acquisition of EVDO.
It'd be pure speculation at this point to predict how well Verizon's network will cope with more and more iPhone users. That said, having the data-hungry iPhone on two major carriers definitely will help spread the load as users switch depending on which is better in their market.
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hsew - Sunday, February 13, 2011 - link
lolnoobs and LOLphone?I lol'd at the speed tests. Makes me wish I bought an iPad when the data was still unlimited.
guest123 - Sunday, February 13, 2011 - link
First off, thanks for the typically thorough review, Brian.I wonder, though, about your conclusion that the Verizon iPhone is "significantly less prone to unintended signal attenuation." True, in the "cupping tightly" scenario the Verizon iPhone is now in line with other leading smartphones, and in the "holding naturally" scenario it improves on the performance of the At&T model. But the Verizon iPhone is still significantly more prone to attenuation in the "holding naturally" scenario than any of the phones you've listed. To me, this was always the real point of the attennagate controversy: as your chart shows, the At&T iPhone is more prone to attenuation when held naturally than other phones are when held in a death grip. Based on your results, the Verizon version has improved, but only to the extent that it attenuates about as badly when held naturally as other phones do when death-gripped. That still seems like a non-trivial problem.
jmcb - Monday, February 14, 2011 - link
I'm glad I'm not the only one who noticed that.....jmcb - Monday, February 14, 2011 - link
Noticed that when held naturally its still worse than any other phone on the list....7Enigma - Tuesday, February 15, 2011 - link
I agree with you as well. I did not like the wording in this section as 99% of people using a PHONE are going to hold it like a PHONE. So while the other numbers are nice to have for specific usage scenarios, the one that is the most important, while improved, is still significantly worse than anything else (other than the AT&T iPhone).mike55 - Sunday, February 13, 2011 - link
I've noticed that the AT&T iPhone 4's have varying degrees of warmer screens than the relatively cooler screen on the AT&T unit you mentioned in this review. I would be interested in seeing how the different screens compare in terms of black level, maximum brightness, color accuracy, etc.Maybe you guys could get a bunch of units and compare them. It would be interesting to see how other smartphones fare in terms of display panel variance from unit to unit. I'm sure all of the display nerds like myself would appreciate such an article. :D
cgalyon - Sunday, February 13, 2011 - link
How does this review not say, "it's the iPhone 4, on Verizon. The radio is different, the rest is the same."?7Enigma - Tuesday, February 15, 2011 - link
If that's what you think why click on the review? And why comment?Voldenuit - Sunday, February 13, 2011 - link
Well, obviously the EU regulatory iconography (CE, CE compliance identifier, CE Alert icon) didn't need to exist anymore since a CDMA phone is pretty useless in Europe.I'm surprised that the FCC label also vanished, though.
LTG - Monday, February 14, 2011 - link
1) Great facts - You somehow took a topic I thought would be a snoozer and extracted quite a bit of interesting detail i hadn't read before.2) Great prose - The general approach, style, and constant attention to what readers are thinking. Feels like we're discovering it all with you.
3) Technical writing mistakes - i didnt notice any! I know it sounds like a really lame point. But it actually is a nice benefit to not be jarred out concentration by typos or grammar mistakes. Its like a luxury on the Internet and makes the experience so smooth.
With all the comments critical of writing here I think its fair to call out the opposite side as well.
Peace -