Apart from Three's offering, we have generally been fed the idea that 4G is a 'premium' product in the UK and as such, we should expect to pay a premium price for its speed. Tesco Mobile doesn't seem to agree.Which is bizarre seeing as it uses O2's network. Anyway, let's look at the facts. If you want 4G with Tesco Mobile, it is free if you sign up to a deal with the supermarket's mobile network.Not that expensive at the bottom end either, with a deal from as little as £7.50 SIM-only. Ok, that only gets you 500MB of data along with your 250 minutes ands 5,000 texts. But you can go up from there to meet your needs. The talking point here is that price is the same as a non-4G deal, which is big news.The downside is of course that use of the O2 network, which is still fairly new and as such, without the coverage of (say) the EE network. But with 13 cities and around 140 towns right now, you might be ok. Check the Tesco Mobile site to see if the coverage is right for you. It should be expanding anyway.It's a move that is significant for Tesco Mobile's business, but it's also quite significant for the entire mobile industry in the UK. It starts something of a price war for 4G and has the effect of making the other major networks look a bit pricey. If Tesco makes a song and dance about this in advertisements (and we're guessing it will), that could force the major networks to price cut too in order to stay competitive.All of which is good news for us, the consumer.