With Asterisk 13 no audio from webrtc to SIP

Hello guys,

I have installed an AsteriskNow 6.12 (Asterisk 13) in a VMware Workstation and I am trying to make a webrtc -> SIP call,
using a SIPML5 client and Bria. The call is connecting just fine, but unfortunately there is no audio.
Anybody some tips?

Thanks in advance