Google isn't technically subleasing spectrum from T-Mobile or Sprint. Google is acting as a MVNO
. They have no antennas that they are using to provide the service. The service uses Sprint and T-Mobile antennas and spectrum coming from the tower. Sprint has 50+ companies using Sprint spectrum as MVNOs. If you examine the list here of authorized MVNO
s, you will see that every wireless carrier has similar agreements.
The reason that this isn't a sublease is that Google has no equipment at the location and no direct lease for operation of a site at the tower. It just legally isn't a sublease.
Google has been rumored to be considering bidding in the upcoming spectrum auction. We would be surprised if they do.