Initial supplies of thecould be limited thanks to "overwhelming global demand", the Korean company has warned.
"We expect to fulfill inventory to meet demands in the coming weeks," a Samsung spokesperson.
US networks Sprint and T-Mobile have already limited the phone's availability to people who buy online, with no specific date on when eager punters will be able to get their hands on one in-store.
"We're anticipating a massive amount of customer interest in this handset and are expecting our stores to be busier than at the height of the Christmas period," said Carphone Warehouse's Graham Stapleton. "We are planning to extend opening hours at our larger sites to cope with the increased demand."
I've contacted other UK phone networks to find out more.
I'd take the warning with a pinch of salt, to be honest, as telling people something is overwhelmingly popular is a sales strategy as old as time. Apple is a past master at it, encouraging people toto be certain of grabbing one on launch day.
Samsung in particular has no excuse for not making enough S4s -- it makes most of the components in the phone, apart from the quad-core Qualcomm Snapdragon chip used in some countries, including the UK.
Samsung's JK Shinthat the different chips were being used to keep supply lines flowing, and that most people wouldn't notice the difference.
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