Verizon Wireless recently unveiled some new postpaid data plans with features popularized by T-Mobile USA, including rollover data and unlimited data that lets customers stay connected at slower speeds after using up their high-speed allotments.

Verizon today announced similar changes to its prepaid offerings with "Always-On Data" that throttles speeds to 128kbps after customers have used up all their high-speed data. While throttled data is less pleasant to use, it's a good alternative to automatic overage fees. Instead of automatically being charged extra after exceeding a data cap, customers can choose whether slow speeds are good enough for the rest of the month or whether they'll purchase more high-speed data.

While the Always-On Data feature costs an extra $5 a month for most postpaid plans, it will be included at no extra charge in the standard prepaid prices. While Verizon raised its postpaid prices and data allotments earlier this month, the prices and data allotments of the prepaid plans are staying the same after today's announcement. It'll remain $60 a month for 6GB of data (or 5GB if customers don't enable auto-pay) and $45 for 3GB (or 2GB without automatic monthly payments enabled). The prices include mobile hotspot usage and unlimited talk and text. But unlike postpaid plans, prepaid still doesn't have rollover data.

Verizon prepaid options also include a data-less plan with unlimited talk and text for $30 a month; customers on this plan can use the Internet on Wi-Fi only.

T-Mobile took notice of Verizon's recent changes, citing them as proof that the US wireless market is competitive. With the Federal Communications Commission studying wireless competition, T-Mobile submitted a filing touting its own positive impact, saying that bigger carriers have been "replicating some of the most popular features of our innovative programs, albeit often without offering the same high level of consumer benefit."

Verizon, meanwhile, took offense to criticism of its recent postpaid changes, writing a blog post titled "Myth v. Reality." Verizon isn't really raising its prices since the price per GB is going down, the company said. While that's true, the cheapest postpaid plan is now $5 more a month than it was before, with the entry-level data allotment rising from 1GB to 2GB.