Carphone Warehouse and the mobile phone company O2 have completely sold out of the standard version of Apple's iPhone after slashing prices last month.
By Jim Reed
Newsbeat technology reporter
A new 3G version of the iPhone is expected to go on sale, possibly as soon as next month
O2 has the exclusive network rights to the phone in the UK with Carphone Warehouse as its high street partner.
Officially, both firms say they are "reviewing stock situation".
But it is thought they are unlikely to order more units ahead of the summer, when a new 3G version of the iPhone is expected to go on sale.
Both chains recently cut the price of the basic 8GB iPhone by £100 to £169. It is still in stock at Apple stores at the original price of £269.
The larger 16 GB model is available from all three outlets at £329.
Customers must sign up to an 18 month contract on O2 starting at £35 a month.
Operators in other countries have also cut their prices.
3G iPhone launch
The 8GB model is available in Germany for around £80 after a price cut from operator T-Mobile.
It is thought that mobile companies are trying to shift a backlog of 8 GB iPhones ahead of the rumoured launch of a new model, perhaps as early as next month.
As usual, Apple is refusing to confirm or deny any of the speculation.
But it is thought the new model will support faster 3G data connection speeds.
The original iPhone was criticised for its slower 2.5G Edge connection.
Internet blogs claim the phone will come with an extra digital camera hidden behind the touch screen to film the user in conversation.
Apple is also expected to replace the standard LCD display with more expensive Organic Light-Emitting Diode (OLED) technology.
That would save on battery life and reduce the thickness of the phone.
As things stand, the iPhone is tied to one select operator in each country although it is possible to unlock the phone to use it on a rival network.
There is speculation that Apple might scrap that system and offer the new iPhone to a range of mobile phone companies at a set price.