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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walmartshopper - Monday, February 14, 2011 - link
"With the phone facing up, the first cellular antenna consists of the new strip at the very top. The second is the strip running from the bottom left, across the bottom, and up the right side of the phone. The far left side with volume buttons and the vibrate switch is part of the WiFi and Bluetooth antenna."In the picture below that, the phone is face down, so shouldn't the colored labels be reversed?
ol1bit - Monday, February 14, 2011 - link
I know in the city it "might" not make a difference, but here in Phoenix, AZ (no hills, etc). My AT&T work phone drops out just driving from Goodyear to downtown on the morning commute (I-10). My Verizon droid does not.Next up: offroading
Doesn't matter where I have been, my AT&T phone lost signal pretty much as soon as I hit the dirt. My friends Verizon phones worked 90% of the time.
So I waited and waited for a powerful Smart phone on Verizon and I got my Droid. No more no-signal! I was on a power line dirt road 30 mile from Prescott with terrain mapping on and seeing the little more that cow trails on one of my 3 day quad trips, it was a big help!! My work AT&T phone dead for the entire 3 days!
So the difference may not be much in the city, but where Verizon really shines is outside of the city. It was simply amazing that I had data so far out and not even voice with my At&T phone.
7Enigma - Tuesday, February 15, 2011 - link
I kept finding myself trying to figure out which phone in your review was the Verizon and which the AT&T. For those of us not up on the lingo of UMTS and CDMA it is a bit confusing. I would have preferred if you had just changed these to say Verizon and AT&T so I could read it more fluidly without constantly having to sit and think which carrier you are talking about.Great review though!
Thanks
chupacabramike - Thursday, February 17, 2011 - link
Guh I can't believe people are still defending at&t service. Look at any customer satisfaction stat..any of them and you will see Verizon soars while at&t sinks. Being able to actually use your phone as a phone priceless. Thank you Apple and Verizon for finally giving us a choice.pshen7 - Thursday, February 17, 2011 - link
Can't wait for the Verizon iPhone! I'm tired of the dropped calls from ATT. My contract is up too so switching should be easy. I'm sure millions feel the same way like I do.Peter, founder of http://koowie.com : Search.Post.Connect.
Laughing Coyote - Thursday, February 17, 2011 - link
FYI, the AT&T iPhone 4 doesn't come with a SIM ejector tool either. Though it apparently does in some other countries.http://www.apple.com/iphone/specs.html
skyflyrr - Thursday, February 17, 2011 - link
Working in the RF wireless field I must commend you on the first accurate tear down and labeling of components of the Verizon iPhone 4.Reviews of Reviews - Friday, February 18, 2011 - link
For a not-quite-so-thorough review of this review, check out www.reviewsofreviews.comfadam - Sunday, February 20, 2011 - link
On the second page, it seems that the paragraph describing the location of the antennas does not match the photo. The text references the iPhone being "face up" while the photo shows the phone face down. The highlighting of the antennas would need to be mirrored in the picture in order to match the text. Really enjoyed the writeup.asandok2 - Monday, February 21, 2011 - link
Thanks for the reply! I thought that would be the case! I found a thread on macforums from last year where a guy speculates that the backplate has something to do with the antenna system too.http://forums.macrumors.com/showthread.php?t=95718...
Any idea if there is truth to his theory?? Is that part of the cellular antenna too?? Thanks in advance!