O2 has said that it will only make the iPhone 4 available to existing customers at launch, on a first-come, first-served basis.
The measure has been brought in to cope with extremely limited stock, O2 said in an update on Friday.
"iPhone stock will be extremely limited in the UK at launch and not everybody who wants one will be able to get one straight away," said the announcement. "We want to make sure that our existing customers get priority so until at least the end of July, only existing O2 customers will be able to get an iPhone 4 from us."
The launch date for iPhone 4 carriers offering the device on a contract basis, including O2, is June 24.
Existing customers, defined as those who signed up for contracts on or before 24 May this year, will only be able to buy iPhones at the company's retail stores, an O2 spokesperson told ZDNet UK on Monday. No date was given for online availability, and the company declined to say how many units were expected to be available.
Mobile, mobile broadband, home broadband and home phone customers will be eligible, said O2. Business customers looking to upgrade should contact O2, said the company.
Existing business customers will be given priority over new business customers, again on a first-come, first-served basis on 24 June. Business size will not matter with regards iPhone 4 allocation, said the spokesperson.
Carriers offering the iPhone include Orange, Vodafone, T-Mobile, 3 and Tesco. O2, Orange and Vodafone have announced UK pricing.
UK demand for the iPhone 4 has been strong. The launch date for SIM-free handsets from Apple slipped from 24 June to 2 July due to volume of orders. Apple on Wednesday apologised that its ordering system could not cope with the sheer number of people ordering the device.