Yesterday, I was trying to send and receive calls, but I couldn't hear the person on the other end. At first I thought it was a jailbreak or unlock issue. I nearly restored the phone to start all over, but... I discovered that the phone thought that the headphones were plugged in, even though they weren't! I'm not quite sure how I fixed the problem, but probably by inserting the headphones, making a call, and then removning them during the call. Now it works normally. Anyone else run into this? Is is a known issue?