Although the iPhone 5 sales have been "very strong" at US carriers AT&T, Verizon, and Sprint, the two older iPhone models -- the iPhone 4 and 4S -- are also doing well, says Canaccord Genuity analyst Michael Walkley. The claims are based on channel checks, and moreover indicate that the iPhone 4 is actually selling out at some stores. In the US, the 4 is typically free if a person locks into a two-year carrier contract.
