O2 is keeping the interest levels up for those who have registered for more info on the iPhone 3G as we edge closer to launch with another mass email on the topic.

But, those hoping to buy the handset on the promised Pay & Go basis will be disappointed as O2's site now says only that it "will be available later this year".

The phone is now available to pre-order on the O2 website with "successful" orders being delivered by courier on the day of launch.

O2 warns: "We do, however, expect demand for iPhone 3G to be very high so orders will be processed on a first come, first served basis so that we can be fair to all customers. Orders will be limited to one iPhone 3G per customer".

Reiterating the 18-month contract tariffs, O2 says the 8GB iPhone "won't cost you a penny" on the £45 and £75 tariffs, and it's £99 on the £35 tariff and new £30 tariff.

O2 states: "Initial, successful orders will be delivered on 11th July by courier and will require a signature as proof of receipt".