Generally, you privatise when you want to save Government money and push the cost to the consumer via companies.
You nationalise when you want to cost Government money in order to provide an standardised service to the consumer. If you want to, genuinely want to, sort out the networks then nationalising the infrastructure would work. But it would cost tax, and you'd still need private industry to handle the rest of the process.
Much like the government-sponsored rollout of telephone lines, or electricity cables, or gas pipes, or water and sewage, used to cost lots of money but everyone got roughly the same service. And once privatised, you can expect to spend more and get less on new installs (hence we're still putting in basic bare copper on new houses) because it's purely a profit motive to supply service.
Every time you privatise an industry, you're just selling consumers to a private company who will bicker and fight every time they need to co-operate.
Every time you nationalise an industry, it's going to cost you a ton of tax to do so and you'll end up with a basic service.
Personally, I think almost everything should be nationalised again because there's nothing a government can't supply at the same price as these companies are doing so, and put the profits back into education, development, etc. rather than shareholder pockets. But the trend over the last 50 years is to privatise even schools, so I can't see it happening.