iPhone5: problem with sound routing when recieveing calls

Hardware and Accessories
Every other time when I receive a phone call I can hear person on the other end for 2-3 seconds. Then the line goes silent: I can't hear anything and neither can I be heard. If I use iPhone without the headset, I move it away from ear to turn on loudspeaker and then move it back. In this case I can continue the conversation. If I use iPhone with the headset, I have to plug it out and replug it in. All that fuzz is nothing but rather annoying pain in the neck, so if anyone could come up with idea or two, I'd be really thankful. P.S.: Sorry if it's already been discussed -- couldn't locate right away...