Cisco says that in 2012, the number of mobile-connected tablets increased 2.5-fold to 36 million, and each tablet generated 2.4 times more traffic than the average smartphone. Furthermore, Cisco expects that mobile-connected tablets will generate more traffic in 2017 than the entire global mobile network in 2012.

Thomas Barnett, senior manager of product & solutions marketing for Cisco, said that the vendor is watching with interest the growth of tablets on shared mobile data. He says if it proves to be a popular way for consumers to add tablets to their data plan it could alter the VNI predictions for tablets in the coming years. AT&T Inc. and Verizon Wireless are both offering data plans where consumers can add a tablet to a shared monthly data bucket for $10. The hope is, of course, that the tablet adds to their monthly data usage and they decide to get a bigger bucket.

Sprint Nextel Inc. CEO Dan Hesse also talked up tablets on his latest earnings call, but said that he didn't want to introduce a shared plan for these devices.

This is no surprise; Sprint currently offers unlimited data for smartphones but caps data for tablets. It would add complexity to introduce a shared plan for both, particularly as Sprint wants to keep unlimited data for 4G phones as a selling point.

What could Sprint do? Perhaps a $20 tariff for tablets on the unlimited plan would work for now? Sprint customers are already used to paying a $10 tariff for smartphones.

I'm not entirely sure how they might handle it yet, but I do know that Sprint should figure out a way to compete with tablet usage on the Big Two's shared plans. As we've seen, these devices will be a bigger part of the picture in years to come.

At the very least, I suspect this won't be the last time we see carriers mulling how to sell tablets to drive data ARPUs while balancing the amount of data they actually consume.

— Dan Jones, Site Editor, Light Reading Mobile