After the iPhone launch was beset with stock shortages and computer malfunctions, O2 must have been hoping that was the end of its problems.
However, reports have been coming in of problems with accessing 3G networks, which is precisely the feature a number of people queued up for hours to upgrade their handsets for.
TechRadar spoke to O2 customer services, which confirmed there was a problem and it was affecting several users.
"There have been a considerable number of people who have been unable to access 3G and The Cloud WiFi hotspots," it confirmed.
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"There has been a problem activating their accounts."
We haven't been able to find out why this problem is happening, or when it will be fixed, but TechRadar has contacted O2 and a response will be winging its way here soon.