I have an iPhone 4, model MD377LL/A, software is iOS 7.1.1, and yes, I have to press 1 to answer all calls.
I tried Apple Genius and they said they had never encountered this problem, and that it is probably a function
of Sprint software.
Please help me if you can, I am at my wits end and am missing a lot of calls.
Thank you Robin
i too am having the same problem. i biught my phone from Sprint Galaxy vS5 aoftware version G900PVPU1AND2