Credit Suisse has published a speculative report on just what might happen to AT&T’s customer base if rival Verizon Wireless were to begin carrying the iPhone. According to Credit Suisse, 23% of AT&T iPhone users indicate they would move over to Big Red if the company was to offer Apple’s smartphone. This would translate into a 0.2% jump in churn for AT&T; from 1.1% to 1.3% in 2011-2012. The report also predicts that AT&T’s 2012 new net subscriptions would fall flat, but Verizon’s net adds would spike to around 4 million. Despite what seems like bad news, the analytics firm upgraded Ma’ Bells stock from neutral to outperform, saying, “it was undervalued compared to Verizon and more prone to upward earnings estimate revisions.” The report also notes that VZW’s cost-per-user would increase significantly upon offering the iPhone but also noted this increase would “snap back” the following year.