Micro SIM manufacturer Gemalto claims that the two networks have purchased hundreds of their cards, which serve the device's 3G functionality.
It is highly likely O2 will offer the device as it has a long-standing relationship with Apple and was the exclusive carrier for the iPhone until September last year, when Orange announced it would also stock the handset.
O2 and Orange may offer the Apple iPad
However, when Jobs unveiled the iPad this week, he said devices shipped outside the US will be unlocked, and therefore available on any network.
The iPad is a slate PC that looks like a big iPhone. It has a home button and an aluminium bezel like an Apple MacBook.
The 9.7in, 4:3 touchscreen is made of glass.
It's only half an inch thick, and weighs just 680g (about half a smallish laptop).
It contains a 1GHz Apple A4 chip, which is both processor and graphics and will come with 16GB, 32GB, or 64GB of flash solid state storage.
Connectivity is handled by 802.11n Wi-Fi internet, and Bluetooth 2.1. It has an accelerometer and compass, speaker, microphone and 30-pin connector.
The iPad will run all Apple iPhone apps straight out of the box - either at their native size or stretched to fit the screen. Users will be able to move apps from their iPhones to the iPad.
To complement the Apple iPad, Apple is launching the iBookstore online store, a kind of iTunes or App Store for e-books.
UK pricing has yet to be revealed, although in the US the device will cost between $499 and $829 (£310 and £515).
See also: 66% of Brits 'unimpressed' by Apple iPad