In this case you could say (again all speculation) that T-Mobile is taking over TALKs coverage zone
That would not be possible because TALK coverage zone is Sprint network. The deal is about MVNO (IMO) because with the merger UMS now has access to both Sprint and T-Mobile network.
Speculation - it could be apple. They're supposedly testing MVNO but denying it.
ITalk Sprint network agreement. We deliver mobile broadband wireless data transmission services primarily under the iData brand to subscribers through our mobile virtual network operator (MVNO) agreement with a sub provider on Sprint's nationwide network that utilizes third generation (3G) & fourth generation (4G) code division multiple access (CDMA) technologies.