O2 has detailed the 4G plans that will be available to customers when the new network goes live on 29 August 2013.

The 4G tariffs on O2 will start at £26 a month (SIM only) and all will come with unlimited talk time and text messages.

The SIM-only packages will start at £26 for 1GB of data and will range up to £36, which will snag you 5GB. There will be options for bolt-ons if you think you'll be needing more data than your tariff normally allows.

If you're after a new handset too, then you'll be looking at the O2 Refresh plan. This tariff set-up will let you update your device when you want, by setting you on an Airtime plan with the handset costs being separate.

The O2 4G Airtime plans start at £22 for 1GB of data and run up to £32 for 5GB. You'll have to add the cost of the device on top of that, which will be between £10 and £25 a month, so you're looking at £32 at the bottom end, or up to £57 at the top, although the device cost will vary depending on whether you choose to pay anything up front for the device.

Those who sign-up to O2 4G before 31 October will get additional data for free. Although the contracts all start at 1GB, those who sign up to the 3GB or 5GB plans now will get more data for the same price, bringing them up to 5GB and 8GB respectively. This additional data lasts the lifetime of the contract, so it's worth getting in early.

The extra-data special offer applies to both O2 Refresh and SIM only plans.

O2 has not yet detailed what it will be offering on 4G pay as you go, but is promising to reveal the details before the end of the year.

Those O2 customers who already have a 4G device will be able to switch to a 4G tariff without taking a new contract and O2 will also be issuing a 90-day Happiness Guarantee: if you're not happy with your 4G experience, O2 will move you back to 3G and give you £15 credit.