Earphones into original dock (iphone5) not working during FaceTime but only for music and videos, is normal?

Hello!

I bought in an Apple Store the dock for the iphone 5 with the line out option. When I use my earphones (the ones from apple), they work only for listening music and watching videos. During the facetime calls, skype etc earphones don't work and the sound comes out automatically from the speaker of the iphone.

Is all that normal?

Thanks a lot