Hi I have an Iphone 4, I have just come back from an holiday in Spain where I had my iphone on aeroplane mode for 3 weeks to make sure I was not charged abroad fees.(I do not know if the first bit matters). Since coming back from Spain I tried to make calls when doing so the iphone would connect to the caller but crackles so you cannot hear them. This happens when making or calls. I tried making calls with my ear to the iphone and even on loudspeaker but it still crackles. I cannot even hear the other person on the other end of the line when calling. I still have bars on the iphone thats fine. Maybe I have turned off something, I am just not sure. I hope you can help. Thanks Ed.