VOIP configuration for Asterisk13, PJSIP, chan_lantiq and Vodafone Germany

I finally found out what's causing the RTP errors.
I had voiceactivitydetection = on in my lantiq.conf, which leads to separate comfort noise packages being sent, which chan_lantiq apparently can't handle correctly (yet?).
Either not setting voiceactivitydetection at all or setting it to sc (silence compression only) gets rid of this error.