Good question ! I think that's one where a mixed approach might be better. There should be a state provider as a baseline, but I think the technology is so complex and advancing so fast that a nationalised utility is unlikely to keep up with all of it, and that's where private companies come in.
But again I believe quite strongly that for national security reasons they should be UK companies not foreign-owned ones. Who knows if the stories of Chinese hardware creating backdoors and kill switches into supposedly secure networks are true, but it's probably not worth the risk.
Most importantly, with so many local and central government functions, banking etc only accessible digitally via mobile phone (a move I detest because it excludes the blind, the disabled and the technologically less adept) I feel that if the government is demanding this form of access, they should provide the disadvantaged a zero-cost way to access it.
RE: Burnham's Buses Are the Right Answer to a Question Nobody Wants to Pay For