My wife's iPhone 4 (Verizon) earpiece stops working every now and then. She has to switch to speaker mode during calls.
To fix this, she plugs in the headphone and unplugs it. Not a bad workaround IMO, but very annoying to her. She's debating selling it on ebay and getting a different phone.
I'm not sure if this is hardware or software related. Any advice? Upgrade the software? Not sure if it will fix it, but we probably will anyway.