I just received a replacement iPhone, due to a sticking home button. The new phone came with 4.1 already installed. I jailbroke with the pwnage tool 4.12, but am now having a problem where sometimes the microphone won't work during a call. I don't think it's a software issue, because it works when using skype, or the Apple's voice memo app. I've restored the phone a bunch of times, but I still have the same problem. Any ideas?