Verizon's "" plans are available now, and replace individual and family plans for all new subscribers. Existing subscribers can hang on to their own plans, but they'll have to pay full price for new handsets (around $600 for high-end phones) if they want to keep using unlimited data.

AT&T's "" plans launch in August, but are not mandatory for new or current subscribers. Also, unlimited data will still be available for grandfathered users who purchase subsidized phones (but, of course, after 3GB each month).

Both carriers refer to their respective plans as "simple," which for any wireless carrier is always a relative term. There's still a bit of complexity involved, and you'll need a calculator handy to see if these plans will save you any money over existing individual or family plans.

To make things easier, we've put together a side-by-side comparison of shared data plans from AT&T and Verizon.

The main difference between the two plans is that Verizon charges a flat rate per phone, while AT&T provides per-phone discounts at higher data tiers. Also, Verizon scales its tiers in $10 increments and never sets each tier more than 2GB apart, while AT&T spaces it tiers more sporadically but offers bigger data buckets overall. Given that AT&T charges $15 per GB for overages, AT&T customers will need to be more careful about which tier they choose and how much data they use.