The mobile operator's 4G network is up and running but those upgrading to the iPhone 5S or iPhone 5C won't have 4G support from launch on 20 September. Customers will be limited to 3G until new settings are available for Apple's new smartphones. See also: iPhone 5C vs iPhone 5 comparison review.
O2 said: "iPhone 5s and iPhone 5c are both 4G ready devices that will be enabled to run on our 4G network within the coming weeks – this will happen when new settings are ready to be sent by Apple and we will inform customers when they are available."
The Telegraph reports, via unnamed sources, that the update won't arrive until at least November. See also: Apple iPhone 5S vs iPhone 5 comparison review: What's the new iPhone got?
"Customers who buy iPhone 5s and iPhone 5c on a 4G tariff before this update happens will get £5 off their bill for one month. Until the update, customers can still use all the data that comes with the 4G tariff and enjoy enhanced versions of O2 Tracks and Priority Sports on our 3G network." it added.
The iPhone 5S on O2 is available for £37 per month or £47 per month with 1 GB or 5 GB of 3G and 4G data respectively. An upfront cost of £119 is required. The iPhone 5C costs £49 up front and £32 or £42 per month will get you 750 MB or 5 GB of 3G and 4G data respectively.
See also: iPhone 5C: UK price.
The tariffs are O2's latest Refresh offering which splits the cost of the phone itself and the airtime to make upgrading easier.
Customers can get up to £280 off the price of the new iPhone 5S or iPhone 5C by trading in an old model.