Starting tomorrow, Sprint customers will be able to get unlimited data for $20 per month on the carrier’s new Starter Unlimited Data Plan and Family Share Pack Plans.

But there’s a catch. It’s not all high speed data.

Under the new plan structure, customers on the Starter Unlimited Data Plan will get 1 GB of high speed data and unlimited 2G data for $20 per month. Unlimited talk and text can be added for an additional $20 per month for a total unlimited monthly plan cost of $40. The plan includes Sprint Global Roaming, which grants customers free texting, free 2G data and calling for 20 cents per minute in 60 destinations around the globe.

“Our Starter Unlimited Data Plan is the most affordable data plan available at any national carrier,” said Sprint CEO Marcelo Claure. “Our customers no longer have to worry about being surprised by costly data charges. We offer our Starter Unlimited Data Plan with 1GB of high-speed data and then unlimited data at 2G speeds. At any time if they need more data, customers can easily add it to their plan.”

Sprint said the unlimited 2G data offer will also be extended to subscribers on its Family Share Pack Plan. The company said customers on either plan who wish to obtain more high speed data will also have the option to purchase more for $15 per additional gigabyte.

The carrier will also offer a $70 Unlimited High Speed Data Plan that will include 3 GB of mobile hotspot usage and Sprint Global Roaming, and will allow additional lines (up to 10 lines) to be added for $60 each.