3 is offering the Apple iPhone 3G S to existing customers wishing to switch networks.
3 is currently not authorised to sell the iPhone in the UK but customers have told Mobile News the operator is now actively offering the device to customers requesting to leave.
Customers on high-end contracts, of £35 per month or above, are being offered the device.
Mobile News understands more than 10,000 iPhones have been upgrded through 3’s retention team in the past six months.
Apple handsets are understood to have been sourced from Italy where 3 is authorised to sell the device.
Sources also claim 3 UK is in talks with Apple to stock the fourth generation iPhone device, which is expected to launch next month.
3 was unavailable for comment.