More than half of the UK's one million-plus iPhone customers have downloaded the new OS3 operating system, distributor O2 said this morning.
This will bring them up to speed with the new 3GS iPhone, which went on sale today.
Customers queued for hours this morning to be among the first to acquire a new iPhone 3GS as it went on sale today
The spokeswoman said O2 was "very happy" with the 3GS's initial sales volumes at O2, Apple and Carphone Warehouse stores since 08.00.
She said OS3, which became available for download from Apple's iTunes store yesterday, was proving a hit with consumers.
She added there was "no truth" in rumours that Apple may appoint another distributor. "We have a multi-year agreement with Apple for exclusivity in the UK," she said. O2 launched the iPhone in the UK in November 2007.
Apple said it would not comment on "speculation".