Nearly a quarter of iPhone users would switch from AT&T to Verizon if they could, when the carrier's exclusive relationship with Apple ends early next year.
According to Credit Suisse, as many as 1.4 million AT&T customers - 23 percent - will defect when they get the chance, if the Verizon iPhone is launched, as Credit Suisse believes, on February 15.
While most are locked into contracts, and therefore likely to wait before making the switch, three percent said they'd be prepared to break their contracts.
Other surveys have shown similar results. Indeed, research from Morpace last month also found that 23 percent of AT&T customers were likely to buy an iPhone with Verizon.
Partly as a result of this, says Credit Suisse, AT&T will only just maintain its level of subscriptions next year. Verizon's, however, will shoot up. Credit Suisse reckons numbers are likely to double, with four million new subscribers next year.
The loss of exclusivity will be quite a blow for AT&T, which signed up about 24 million customers for the iPhone in the second quarter of this year. Indeed, the phone accounted for 30 percent of all the company's new subscriptions in 2009 and 2010.
Nevertheless, Credit Suisse thinks it will weather the storm, and has raised its rating to 'outperform' from 'neutral'. "The impact from the loss of iPhone exclusivity should be substantially less than current valuations imply," Credit Suisse analyst Jonathan Chaplin wrote in a client report seen bby Bloomberg.