iPhone Does Not Ring, Calls Go Straight to Voicemail

Several users have experienced an issue in which the iPhone 3G does not ring and calls are, instead, routed straight to voicemail. Of course, this can occur if the iPhone is off or the signal is weak or non-existent. However, several users have reported this behavior even with a full available signal.

Among the user reports from this Apple Discussions thread:

• "Around November 15th, I started seeing some of the same problems on my iPhone 3G (calls not coming through, voicemails & texts getting delayed, unable to make calls / send texts)."
• "It seems totally random when it happens to me. On the one hand, several calls will come through as expected, no problems. Then there will simply be a "voice message" tone and the on-screen message saying that someone had left me a voice message - while the phone sits next to me, fully charged, silent."
• "Just wanted to say that I have the same problem... Phone with good signal but no ring and straight to voicemail."

Possible solutions for this issue:

• Turn off Bluetooth in Settings
• Turn off WiFi
• Turn off 3G
• Replace your SIM card (requires contacting your provider)
• Reset the iPhone: Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears.