Remember last year, when AT&T was about to lose its iPhone exclusivity to Verizon Wireless? If you live in America, you probably do. AT&T's advertising shifted in tone, moving from espousing the virtues of the iPhone generally to calling out its more esoteric features. Features that the Verizon version couldn't match.

On the iPhone, that's something of a tall order. Apple exerts more control over the user experience than any other American manufacturer, a tight grip it's maintained since the first iPhone launch in 2007. Cupertino likes to keep the user experience as uniform as possible across all iPhones, no matter what carrier is providing the network connection. There's no skin to customize on iOS phones, and very little -if any- bloatware. There's not even carrier branding on the casing. Aside from some miniscule antenna design differences and disparities in data speeds, it's almost impossible to tell a Verizon iPhone apart from an AT&T one.

But feature-wise, there's one very important distinction between the two iPhones, a difference we don't hear much about anymore. Something the AT&T version can do which the Verizon version can't: simultaneous voice and data. That's a capability that Ma Bell started throwing in Big Red's face even before the latter secured its own iPhone:

And nothing's changed now that Verizon's gotten its hands on its own slice of Apple's finest. Right down to the vanilla use case and the tired old "guys always forget anniversaries because they're guys and isn't that just the cutest thing " joke.

Technically explaining the reasons for this usability gap would require diving pretty deeply into network architecture discussion, not to mention calling up a different writer. But on its face, the issue is simply stated: at the time these ads aired, devices built for Verizon's 3G network, based on 1xRTT and 1xEvDO CDMA, couldn't provide data access while a voice call was in progress. AT&T's network, by contrast, was built according to the 3GPP standard; it's HSPA network had, and continues to have, no trouble supporting a user's data connection while a voice call is in progress. CDMA networks like Verizon's have had available upgrade paths for some time, but the carriers haven't opted to use them. Until now.

Verizon, along with its smaller CDMA-based rival, Sprint, has begun using a network technology called SVDO, first announced back in 2010, to provide its customers with concurrent access to voice calls and data usage. Most of the carrier's 4G phones already provide this functionality, by virtue of the fact that the devices are using two different networks simultaneously. But SVDO is important because it provides this same talk-and-surf ability to 3G-only devices. The technology requires special hardware on the user's end, meaning only newer phones can take advantage of the feature, but the upshot is that CDMA users in the United States are finally starting to experience the glory of speaking while cyber-surfing from their phones.

MULTITASKING! WOO!

The question is: why do we want to? Are we already such a scatterbrained culture, so chained to the need to perform many tasks at once, that we can't stand the notion of being disconnected from our data for the brief span of a phone call?

Well, yes. But that's okay.

AT&T has already done a good job of "selling" this feature with the commercials embedded above, among others. Data usage is indeed helpful to look up movie times for the friend who's on the phone, or to send a picture message to answer the question "which hot dog stand are you at?" It's crucial when trying to meet someone else in an unfamiliar place, where you want to be able to consult Google Maps on the fly while they talk you through the twists and turns of an urban canyon.

Anyway, it beats this.

But those are all yesterday's use cases. For me and a host of other connected people, they're so common as to almost seem passé. Data is so critical to our existence now that suspending access to it for a voice call sometimes means the difference between making or breaking plans. Nowadays, the thing we're most worried about missing is data-based notifications; I constantly receive tweets and emails while I'm on a call, and sometimes they alter whatever plans I'm busy making with the person I'm talking to. Maybe that means I don't plan things out well enough, but I know I'm not alone.

Data in the midst of voice calls also grants us the joy of sharing in the other direction: outbound. Commenters sometimes lambast me for suggesting that "joy" is a critical component of mobile communications, but guess what? It is. Mobile phones exist not just to increase business efficiency or public safety, but to delight us. Sharing may not always be caring, but it's usually fun. And it's great to be able to share a photo of a beautiful sunset with a distant friend while she's on the line, rather than being forced to say, "wow, you should see this" or the worse-still "hang up so I can send this picture and I'll call you back."

Unless and until video calling takes hold in a big way, we're still going to run into a lot of those situations. And it's good to know that, thanks to the continuing evolution of mobile telephony, we'll be able to do so. Even if the gradual inclusion of this increasingly common feature flies under most of the public's radar. Even if most of us take it for granted.

And even though we dumb 'ol guys still can't keep anniversary dates in our clunky noggins.

Do you use simultaneous voice and data for work? For pleasure? For convenience? For fun? If so, let us know how in the comments below. If not, let us know why not in the same section ... once you're done with that voice call.