Hi all, I've been experiencing and issue with my iPhone 5s a while ago. I replaced it last December because a problem with the home button. After I replaced it, it began working great! Anyways, since April, I'm not able to make or receive calls. I've searched all over the web for a solution, but with no success. Data works fine, FaceTime, Skype, Whatsapp and Tango calls works excellent both in 3G and on WiFi. Speaker works great, the mic works fine, I tried with Siri and the response is as great as before the problem began. I've tried calling wearing headphones and through bluetooth but again, calls (from the carrier) won't work, VoIP calls (FaceTime, Skype, etc) work fine. It's really weird! I've placed my SIM card in another phone and there calls work. I've also placed someone else's SIM card on my phone and problem would persist. I need help, I'm desperate! I tried going to an Apple Store, but my warranty is due, so they charge me around 250 dollars for the replacement of the device. The Genius bar opened it and cleaned it. They told me that the phone looks fine and shows no sign of damage. I take great care of my phone so I don't know why this is happening. Has this happened to any of you? Please help.