iPhone app "rejecting" incoming calls?

Question

A client of mine just informed me that, while using the app I am developing for them, they received an incoming call, but it did not bring up an alert on the iPhone. Instead, the person making the call heard a message that the user's service was temporarily unavailable.

If we put aside for a moment the possibility that either the person making the call did not have a signal to make a call, or that my client did not have a signal to receive a call, is there any conceivable way that my app could have silently rejected the call? I don't think that's possible. My interpretation of the Apple docs tells me the iPhone OS is in full control and should be able to terminate my app if it wanted.

Am I missing any corner cases here?

Answer 1

There's no programmatic way to do it.

However if you're testing on an EDGE network, Jeff Kelley's answer is correct.

Answer 2

Are they on EDGE? While using EDGE, you can't receive calls. They share the same radio.