O2 is boasting thousands of iPhone sales since the device launched in the UK last Friday - but its activation infrastructure is feeling the pinch.

Reports have been emerging that claim some users attempting to activate their iPhone using iTunes have seen the application crash after they enter their credit card details.

An O2 customer support representative today attempted to pin the blame for this on Apple and iTunes, according to a Macworld informant. However, in discussion with the activations group at O2, the informant learnt that the fault is in fact with O2's server-side infrastructure for processing such exchanges.

It appears O2's infrastructure is having a tough time coping with the iPhone-led demand. Many iPhone owners who don't meet the credit risk evaluation the system runs on new customers are being asked to file a £100 deposit when they try to activate their iPhone. It's this which is causing the problem, because the system is prone to failure when they attempt to input this payment.

Some additional information pertaining to iPhone activation is available from Apple's tech support website.