Apple has released iOS 6.1.1 for iPhone 4S owners in order to address the 3G issue that was experienced by some users after updating to iOS 6.1.
Apple explains that the update, which was released on Monday, "fixes an issue that could impact cellular performance and reliability for iPhone 4S."
On Friday, Vodafone warned its UK customers with the iPhone 4S not to upgrade to iOS 6.1. Texts were sent out to iPhone 4S handsets which read: "If you've not already downloaded iOS 6.1 for your iPhone 4S, please hold off for the next version while Apple fixes 3G performance issues. Thanks."
On its website, Vodafone wrote that "some customers may occasionally experience difficulty in connecting to the network to make or receive calls or texts or to connect to the internet."
"Apple is working on a solution to their software issue. These connection problems are intermittent," Vodafone added.
While the iOS 6.1.1 update has only been issued for iPhone 4S owners, some iPhone 5 owners have also has issues with the update.
Users on Apple's iPhone support forum have reported a big drop in the battery life of their device after updating to iOS 6.1.
Apple released iOS 6.1 on 28 January, which introduces a few minor – but welcome – changes to the software including the reinstatement of iTunes Match features, a Reset Advertising Identifier and more LTE coverage.
On 6 February, Apple seeded the first iOS 6.1.1 beta to developers, an update that brings major enhancements to Maps for Japan.
It is unclear whether Apple will release a separate iOS 6.1.1 update for iPhone 5 owners.