I've been doing a lot of traveling lately, and as a result, have been experiencing areas of the country with spotty coverage. To that end, I've been experimenting with video calling over Wi-Fi (see my Nexus 7 review) and even using Skype on my iPhone on AT&T's 3G network as an alternative to traditional voice calls.
I recently had two occasions to use Skype as a power-user while mobile. I specify "while mobile" since I'm a daily user of Skype on my laptop, both for Skype-to-Skype calls and for Skype-out, where I pay about $30 a year and can make unlimited calls to mobile and landlines in Canada, Guam, Puerto Rico and the United States.
The first occasion presented itself while I was riding in the passenger seat, on the way to a business meeting. I was on my iPhone and kept dropping the call. I finally suggested that we try to go Skype-to-Skype while mobile, and see if it was any better. If you've ever used Skype, you know that the call quality is immediately better, but the surprising part was that we not only were able to hold our call, without drop off, across two states, but we were also able to video conference, via Skype, iPhone-to-iPhone. This is important to note for two reasons. First, previous attempts to talk to someone across two states, without any drop-off, have never succeeded for me. Second, the video was streaming over AT&T's 3G network, and stayed consistent throughout the trip. I should also mention that it wasn't blotchy or loaded with digital artifacts--I could perfectly make out the face of the person I was speaking to. It was actually very close to the Wi-Fi Skype-to-Skype experience.
The second occasion for using Skype instead of cellular to make calls was when I was vacationing. We had spotty coverage in the condo, so to make calls from my mobile, I launched Skype and then initiated the Skype-out calls directly from my iPhone, while tethered to the condo's Wi-Fi. The Caller ID on my Skype account shows up as if I'm dialing from my mobile, so anyone receiving calls from me had no idea I was calling via Skype and not from AT&T's voice line. I also stepped outside of the condo, and hopped on AT&T's data network and initiated additional calls, when I couldn't seem to get a regular voice call through.
If you haven't been following the news, iOS 6 will allow FaceTime calls over a cellular network. This is big news because the carriers are going to be forced to offer video calls over their cellular network. Depending on the carrier, you'll either have this as a no-cost add-on (Sprint has already said that they're going to offer it at no additional charge) or you'll need to be on a special plan, like AT&T's Mobile Share data plan.
You could argue that carriers have already embraced video calls over their network, since you can do Skype, Google+ Hangouts, and others. However, these are all running on the traditional, un-throttled data network. You could see a future, starting with FaceTime, where the carrier prioritizes FaceTime calls and ensures better call quality, for a premium, of course.
With iOS 6 due in September, Microsoft controlling the future of Skype, and Google innovating with Hangouts, this is going to be a great space to watch. Regardless of the outcome, it's pretty clear that the lines between data and voice are blurring.