Since CDMA can't do simultaneous voice and data, does all the syncing in the background have any impact on the phone's ability to receive calls? I have had several calls go directly to voice mail and wondered if this might be an issue.
It shouldnt . I actively use data all the time and have not had an issue with calls coming in. I often see incoming call notification as I am loading a web page. Typically a call will not go through if you have a brief loss of signal to the network or a bad connection when roaming. For example when we are at our summer home there is something in the area that interferes with cell networks in general. I do experience missed calls that never made it to our phones. This is also not only sprint it happens to. We know people there with ATT and version that the same thing happens to. I hope this helps answer your question.