What does this mean with my iPhone 5?

I have a friend that is in a third world country in Africa. I tried calling her cell phone with my iPhone 5, and it rings four times, then beeps three quick times, then it says "call ended." It doesn't even take me to her voicemail. What does this mean?

The "three beep hang-up" usually happens when reception is not good enough to continue the call. It happens all the time to me on the subway or in elevators. Perhaps the service is not good enough either where you or she are at the time to carry out the call. You can always call apple support if the problem persists.

Its a network problem try again later

NO voice mails in Africa if there's a network disturbance.