TiPb Answers: Verizon iPhone and the limitations of CDMA

TiPb Answers: Verizon iPhone and the limitations of CDMA

While many have been waiting a long time for the Verizon iPhone, the same CDMA network that gives Verizon its terrific coverage and reliability brings with it a host of other problems, including the famous lack of simultaneous voice and data and limited international roaming, but also some lesser known issues such as split SMS messages and greatly reduced conference calling options.

None of these are new to the Verizon iPhone but they are new to iPhone now that it's on Verizon, and new to users who haven't experienced CDMA before. We'll take a look at them after the break.

No simultaneous voice and data

Verizon runs on CDMA2000 using EVDO Rev. A for 3G data (see our wireless networking guide for more on what those terms mean). EVDO Rev. A does not support simultaneous voice and data the way AT&T (and other GSM carriers) HSPA networks do. That means if a call comes in while you're using 3G data -- surfing the web, Skyping, sharing your connection via personal hotspot -- you can either ignore the call and continue using 3G data, or answer the call and effectively put your 3G data connection on "pause". If you're on a call you won't receive email or push notifications and if you try to surf the web or download an app you'll be informed you're not connected to the 3G network. Once the call ends, 3G data reconnects and you can start using the internet again.

If you're on Wi-Fi as opposed to 3G data you can make calls and use data without a problem. It's only 3G that cuts out during calls.

Verizon has chosen not to roll out EVDO Rev. B, which does support simultaneous data in favor of more quickly deploying a 4G LTE network (currently a hybrid CDMA-voice with LTE-data network, in the future a Voice over LTE network). They are rolling out Voice over Rev A (VoRA) aka SVDO which will allow for simultaneous voice and data on future CDMA/EVDO phones, but not the Verizon iPhone. (See The Cell Phone Junky for more on the technology.)

Limited international roaming

GSM/HSPA, the standard used by AT&T and T-Mobile in the US, is far closer to being an international standard than the CDMA/EVDO technology used by Verizon. While there are a few other CDMA/EVDO networks in North America and Asia, GSM/HSPA is supported throughout most of the rest of the world, including Europe. If you use a Verizon iPhone there are a limited number of countries where you'll be able to roam. Verizon does offer loaner GSM phones for international travelers but that's not as seamless a solution as GSM iPhones that can intrinsically roam around most of the world.

SMS/Text splitting

SMS/Text messages are limited to 160 characters. On AT&T and other GSM iPhones, if a message exceeds 160 characters it will still be shown as a single message to both the sender and receiver. On Verizon once an SMS hits 160 characters, any additional text is split off into a second message, after 320, a third message, etc. The same content is still delivered, it's just not presented as nicely. (In some cases the message parts might even appear out of order which is even more annoying.)

Limited conference calling

Verizon's CDMA network only supports "3 way calling" so you can only enter into a conference call with up to 2 other people (3 including yourself) at the same time. It doesn't matter if iPhone can handle more, Verizon's network and hence the Verizon iPhone is limited to 3-way calling.

Likewise, 9to5Mac points out that handling conference calls is also more challenging on the Verizon iPhone since you can't take one party "private" or hang up on one caller while keeping the other active. (It hangs up on all callers.)

Apple provides the following diagram in their knowledge base:

Verizon iPhone and the limitations of CDMA

That network

So yes, overall there are a lot of limitations to the way CDMA handles voice. However, if Verizon has great coverage in your area, you're on Wi-Fi when you want to talk and surf, you rarely if ever travel internationally, split SMS/Text messages don't bother you, and agile conference calling isn't a must-have business feature for your iPhone, you may not care.

Otherwise it's a compromise. Decide what's most important to you and which carrier best provides it. If anything is a deal-breaker, then that makes your choice much simpler.

For more information and help check out our Verizon iPhone Forum.

Have something to say about this story? Leave a comment! Need help with something else? Ask in our forums!

Rene Ritchie

EiC of iMore, EP of Mobile Nations, Apple analyst, co-host of Debug, Iterate, Vector, Review, and MacBreak Weekly podcasts. Cook, grappler, photon wrangler. Follow him on Twitter and Google+.

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TiPb Answers: Verizon iPhone and the limitations of CDMA


The SMS/Text splitting only applies to the receivers of non-smartphones. My BB Storm would combine messages of over 160 characters into 1 message, same with my Droid and the same with my Verizon iPhone without a problem. Only the regular phones have that issue of seeing the only long message split into different messages and possibly out of order, my first Verizon phone, the Samsung Alias had that issue.

It sent it as an mms and not a sms message sometimes phones will automatically do it. That is how it showed up as one message.

Actually, it uses enhanced SMS, not MMS. As do all other Verizon smartphones, and quite a few feature phones.

Re: Verizon has chosen not to roll out EVDO Rev. B... Phones have to be capable of it. So far, the only phone Verizon has that is alleged to be capable is the HTC Thunderbolt - a "4G" phone - and Verizon is not officially supporting it, but acknowledging it (the Thunderbolt) can do simultaneous voice & data on 3G.

I texted my brother a message with less than 50 characters, who has a verizon iPhone and I have the AT&T iPhone, and the message was still split... And when I showed him the message on my phone he couldn't believe that such a short message would still b split into two... However it doesn't really bug us cuz he understood what I was trying to say...

All those verizon limitations are not enough for me to stay away from switching over to the big red when iPhone5 launches in the summer. AT&T has been so horrible here in NYC that i don't care at this point all the ETF fees that I will have to pay. At this point I'm leaving AT&T in a few months because I HAVE to.
All the endless amount of dropped calls when I'm driving through a populated area, all the times I felt like throwing my beautiful iPhone out the window because of a network failure- you think the lack of conferencing calls will make me think twice of dropping AT&T?
Talk n surf at the same time to me is soooo overrated when I'm barely able to sustain a PHONE call on this crappy network as it is. I'm sure Atnt is fine in other cities but they're an absolute joke in the big apple.

Why is Tipb so anti verizon. I haven't payed attention to Tipb in a few months but it sure has turned into a different place.

these are facts, not opinions, what might work in your area it might not work on mine, these are things everyone should take a look at when picking between at&t and verizon.

Exactly! Nobody thinks twice when an article literally tears AT&T apart, even though it's apparent now that more people are happy with them than previously believed.
It would be irresponsible to not give Verizon the same run down. There are good points and bad to both carriers, and now it's time to cover those on Verizon since they have the iPhone as well.

It's because they can use the iPhone's primary function without dropping calls so they need to say come of the cons about Verizon.

@Gino thanks for the great comments. People keep acting like the iphone isn't supposed to be a phone!!!!! I remember how mad i used to get when my 3gs would drop a call. I switched to VZ in sept and it was the best move ever made. I wish VZ would actually stop the BS and remember that the iphone's primary function is still being a phone.

@Jeff What's funny is that most comments these days are accusing us of being anti-AT&T and paid off by Verizon. I guess it's just easier to feel picked on? :p

I don't get it. I've never had a need to surf the web and talk on the phone at the same time ON MY CELL PHONE. Are so many people doing this that makes it such a big deal, or is it just something to bag on CDMA networks about? Also, the whole worldwide roaming is lost on me...how many of you out there are REALLY world travellers in need of being able to roam from a US network to one elsewhere in the world? You must have much more free time than I...and a whole ton more money. I guess I don't see the big deal.

It's something to "bag on"... and the 'World-mode' thing is pretty much the same - anyone who has a need to use technology while traveling will more than likely know what they need to do to meet their needs. Most of this stuff shows up on blogs because they need to write about something, sometimes anything to have new content and generate hits, and comments :)

Actually you must have more free time if you have time to not multi task. I use the talk and surf all the time, great benefit. And if nothing else it gives you the option. Not having that ability limits features on your phone like mobile hot spot etc. The iPhone isn't just a phone and to think that is all it is for is crazy and you are limiting yourself. Fortunately I get great ATT service in my area, and left VZN for ATT. Obviously that isn't the case for everyone, but for all the reasons above and more are why I am sticking with ATT.

I work in the wireless industry. I dont understand why any difference between 2 phones are so compared under the microscope. First of Verizon has what over 95 millio customers. 2nd ATT has what over 95 million customers. People on Att know there service sucks but they pay for it. It like you know across the street the Gas is $.10 chepper but you wont go across. Or you know when your standing in Line at the movie theater behind 10 or 15 people and the window to the right has 1 person in it but human nature is to follow not lead. Verizon doesnt care if you phone works in Mexico, Canada or Europe or in fact anywhere else in the USA. All that is 2nd. I keep seeing this international stuff braught up. How many people go international with there att phones? A minority. Guess what Verizon has the Majority in favor Having the best network in the USA with the numbers it has people with brains stay with Veirozn. They dont care that there text breaks up or that cant go to Europe and use there phone when there never going (lol). I know you guys need stuff to write about but come on. All these sites and repetation of others. Stop Copying and Pasting.

I am glad you like Verizon, but people who use ATT are not lacking brains. In Texas ATT is great. Most of the ATT bashing seems to come from New York City and San Francisco, where the mainstream media and the tech media are headquartered. In the rest of the country, the two networks are pretty much on a par. I have been satisfied with service on ATT, but competition is good, so I welcome Verizon to the iPhone family.

@Zane: AT&T sucks hard in Texas. I've been here a few months and the service goes like this.
Calling............ or Call Failed.

I care about my texts breaking up and my data speeds. The hubby thought he did not care until he got his vzw iphone. ESPECIALLY when we test his against my AT&T iphone. Go figure.

I am not in favor of either carraier. I lake Chocalte you like Vanilla thats how my thinking is. The only reason Apple choose GSM first was pocket. They knew they could sell the phone world wide for more revenues. It doesnt matter people are in San Fransisco or Texas. When you buy a phone from a National Carraier it doesnt MATTER WHERE YOY ARE OR IF YOUR PART OF MEDIA> WHY ARE CALLS DROPPED? Att then should adverstise "Hey your phone doesnt work, Move to Texas there internet is fast and can make calls or Nebraska? Come on really? If you phone works use it if it doesnt loose it.

I live in Washington State and call quality is great. I could see cities with a saturation of users could cause poor QOS. Verizon will help balance the load over the next few years

I lived in Gainesville, FL-- far from a saturation of users and call quality sucked if I could even get a call out at all. So it doesn't necesarily have anything to do with the amount of users in the city.

Why do people keep saying surf the web and talk? It's not just surfing the web. It's google maps, some navigation, any app that goes though the web, no email. For some people this is a big thing. I use this feature 2-3 times a day. And these people that have some many dropped calls with AT&T where do you live under a rock. I've been in almost every state in the us and always had service and made and received calls just fine. If it's that bad then why not go to a carrier where not not gonna have this problem? Some people like to bih just to bih.

I am on AT&T in NYC and I travel frequently out of the city a bit upstate. In a populated area in Brookyn my data speeds are sub 2mbps. However even in an area where i have 1 bar of service, no dropped call has happened thus far. When I go upstate I get 4+mbps data speeds and no dropped calls.
As for browse and talk at the same time, I do that from time to time. When I wait on hold from any one of the companies I call, i put it on speaker and do a little facebook, tipb, you name it.

Ha! I have AT&T and nary a problem. However, I do travel to the UK. The last time I traveled with my iphone 4 with a $50 data plan I had a text message the evening of the first day saying I'd exceeded my data plan. A word to the wise, pick up a local sim and use that when traveling overseas.
I very rarely use voice and data at the same time, altho I could I suppose.

As with things it comes down to personal preference and requirements. Left ATT iPhone last year for a VZW Droid Incredible because ATT service sucked at home location. Never regretted it and the subject issues have not been a problem. When VZW iPhone 5 comes out will consider switching but not a slam dunk!

Split SMS happens to iPhone users regardless because we all message at least one person on another network which is likely to also be a CDMA network. Another annoying thing by CDMA networks is Ghost SMS. I had a really bad case of that back a few years when I got 9 back to back messages from a friend on sprint. I still get double or triple messages from friends on Sprint and Verizon.

So what I hear you saying is that if you want a TRUE iPhone experience, get the AT&T version and not the Verizion one. Is that what I am hearing you say?

I can say this about Verizon. I was in a wreck in Memphis. I have an At&T Iphone3gs, Cellularsouth balacberry pearl flip, and a Verizon droid x. Tried to call 911 on att..no good dropped call, on cellularsouth, same..dropped call. The only one we got through on was the droid. The only reason I have three is due to my job. I will be cutting down to one now. What is really bad is there were three of us in the car and all of our phones had full bars. Only the droid worked. The other phones were At&T or cellularsouth.

I really want to do the Iphone on Verizon but really need voice and data at the same time. I do a lot of conference calls over webex and would like to see the presentation as well as participate in the conversation.

VERY VERY VERY minor issues when compared to a BAD VOICE network like AT&T's ... The worst network in America.
Yes some ppl have had more luck with it than others but overall .. it's a horrible voice network.

re: "Voice over Rev A (VoRA) aka SVDO"
No. VoRA and SVDO are two different technologies. The first is a voice over data channel method. SVDO uses two radios so one can hook to voice, the other to data.