well, around ~2011 network operators discovered that it's possible to virtualize network&compute, i.e. run routers, switches and computers in VMs. As result of

well, around ~2011 network operators discovered that it's possible to virtualize network&compute, i.e. run routers, switches and computers in VMs. As result of this they came up with a grand plan where they will stick everything to virtual machines on top of cheapest hardware (preferably). A bunch of conferenced happened in order to define standards for all this happy future. Only most of it crashed and burned for multiple reasons. But it was back then. Now, in theory, it's pretty much possible to run operator based on leased lines (many operators actually run over leased lines anyway, in many countries and they don't own physical fiber networks due to regulations or other reasons), and interfaces with antennas/enodebs that are "virtualized" (to support multiple operators at once) or even using cloud-ran while deploying rest of software stack "in cloud".