FreedomPop has carved out a bit of a niche for itself with a free pricing model that customers can add the options they want to a la carte, and it seems that they will be licensing the technology that enables that model to a "major U.S. mobile operator" at some point in the near future. A deal allowing European carrier Wind-Hutchison Italy to use the technology is reportedly already in the works, which is said to entail the carrier gaining access to FreedomPop's "proprietary" Wi-Fi first technology. This would give the carrier the ability to generate a free user base, and eventually convert some of them to paying customers. According to FreedomPop, this modus operandi tends to net roughly "fifty percent service revenue margins" when all is said and done.
FreedomPop did not reveal which US carrier they plan on working with, which has some fairly interesting implications, given how easily they handed over the identity of their European cohort. It should be noted that FreedomPop has said that they are planning on signing even more deals of a similar nature across multiple countries, which could mean that more than one of the big four US carriers could end up taking advantage of their freemium approach. FreedomPop, being an MVNO, piggybacks off of different carriers on a region by region basis, with Sprint being their choice for their US operations. While this link is a plausible reason to suspect Sprint as the US partner that will be the first to get FreedomPop's free-with-caveats approach on their own network, nothing has been confirmed just yet.
AT&T, at the moment, is having some issues with postpaid user acquisition and retention, and also managed to fall short on OpenSignal's latest carrier report. This one-two punch of bad luck means that AT&T could benefit from the near-guaranteed influx of users that a major carrier advertising a free option would bring. Sprint, on the other hand, is already FreedomPop's closest US partner, and could use the option to volume-boost their public image of having great value for a wireless customer's money. T-Mobile is in the middle of once again reshaping their image, and jumping on such a prospect would definitely up their maverick cred, and likely end up pushing other carriers to work with FreedomPop. Verizon, last but not least, is largely seen as the luxury carrier, and could certainly use a free option to attract those who want Verizon's network, but don't want to pay Verizon's prices for it. It's plain to see that all four carriers have deep motivations, so the aforementioned partnership with Sprint is the only shred of evidence thus far as to who they might license their technology to first in the US.