Yeah I assume since it's not at all taxpayer funded, it looks something like: 1. They build a network on their own dime in the tunnels 2. They pay MTA "rent"

Yeah I assume since it's not at all taxpayer funded, it looks something like: 1. They build a network on their own dime in the tunnels 2. They pay MTA "rent" for the privilege 3. They have an exclusive contract so other carriers pay them to use their infrastructure. AT&T, Verizon, etc. essentially operate as MVNOs in the tunnels.