They’re not going it alone; ONOS [1] is basically the open source carrier-grade networking platform. Think of it as Kubernetes for SDN packet routing that they’re building custom network integration solutions (think routers, bulk fiber termination, RF, satellite, laser, WiFi mesh) on top of. Then get Chinese manufacturers to build the hardware (which doesn’t have anything proprietary in it — all white box with Intel or ARM CPUs).
Incredibly powerful and flexible, and they have all the heavy hitters involved (Google, Intel, Samsung, AT&T, Comcast, etc.) It will be a game-changer for telecom in another 5 or 6 years once the management tools mature and commercial solutions based on it are developed.
Tell us what are the great alternatives in middle end.
I suspect (in the US) that many VPs of Telcos are best buds with major hardware vendors. Telcos run legal monopolies, there's no incentive to be disruptive.