Why Simultaneous Data and Voice on Verizon's iPhone Doesn't Matter

In the wake of the announcement of the Apple iPhone 4 on Verizon, one question I’ve seen come up is if the Verizon version will be able to use voice and data simultaneously, as on AT&T’s version.  Typically, some of the answers to the question range from the half-right to the hilariously incorrect with a lot of confusion in between. I think a better question would be: Does it even matter at this hour?

In order to understand why AT&T touts simultaneous voice and data as an advantage, you have to look at their network. I’ll get to the iPhone in a bit.

5MHz channel to transmit voice

UMTS uses a 5MHz channel to transmit voice and data over the air, with the capability to furthermore “split” the channel into two 2.5MHz sub-channels in case one person is sending both voice and data together. Opposite, Verizon’s CDMA network uses a much smaller 1.25MHz channel to send voice and data, with no way to split the channel furthermore, forcing either data access and no voice calls or voice calls and no data access.

With that out of the way, you might be wondering how Verizon is able to offer Skype Mobile on its phones since it requires both a voice and data plan. Simple: a little network and software trick called IMS or Internet Multimedia Subsystem.  IMS is built into a CDMA EVDO Rev. A network and overlay by converting the initial outgoing call into a data session, “moving it” onto the data network via application and network flags. The carrier has to turn on the IMS on the backend in order for simultaneous voice/data to work and the developer has to include the support for IMS into the program, if not it’s not going to work.

Now, back to the iPhone. Reports started coming out last summer that Verizon was working on Voice Over Revision A for the iPhone. This is IMS, it is not new nor is it exclusive to the iPhone as many erroneously reported.

The iPhone 4 will not support simultaneous data/voice

Now that its been confirmed that that the iPhone 4 will not support simultaneous data/voice, is browsing and talking on the phone actually that important to current and potential iPhone users? Only if you care about bullet points. The reality is that few, if any people will as a matter of fact use such a feature frequently enough to take it into account as a purchasing decision and only see it as a novelty.

Sure, it would be nice to talk on a headset and browse on Mobile Safari on Verizon’s network together, however that would lead to intense battery drain and temperature issues as the chipset would be handling a phone call over VoIP (Voice over Internet Protocol) and a data session over EVDO, something that’s conveniently overlooked on AT&T’s claims. To tell the truth, the only people that see it as an advantage are those that care more about spec sheets than real-world utility. Just try using AT&T’s impacted data network… with half the bandwidth you as a general rule get.

Should you worry about the possible availability or lack of simultaneous voice/data on the Verizon iPhone? To my way of thinking, not one bit.

Lot of simultaneous voice

Actually I use a lot of simultaneous voice and data together. As an Network architect I’m often using logmein and other remote apps on 3.25G or whatever its called nevertheless, during talking on the phone to the local tech.

I’m sure there are specific usage scenarios, nevertheless even in those cases, I tend to agree that it is more of a buzz feature… Wi-Fi is going to be necessary for business-critical situations, especially on an impacted network like AT&T.

nanfy,you apple fanboy’s are all alike,you will defend at@t and apple to the death,you know the cartoon on youtube if apple put out a brick and called it a iphone people like you would for all that buy it and scream to the heaven’s about how great it is.verizon and att both have the iphone it’s a win win for the consumer’s.

I don’t have an iphone nor would I ever pay for ATT or Even verizon service. I have a company provided tmobile G2 and my personal phone is a sprint samsung epic 4g with 9 lines pursuant to this agreement my account. So please don’t generalize at once time. You seem to have forgotten that tmobile is as well gsm and can do voice and data together.

The original 2G iPhone on ATT it

When I had the original 2G iPhone on ATT it was a bummer because I couldn’t surf the web if I was waiting on a client call, if not the call went to voicemail. Don’t know if that’s an issue for Verizon.

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