Rejecting secure audio stream without encryption details

i am try to make call from firefox using SIP5ml to the Zoiper SIP client but asterisk shows the following warning even i installing the webrtc4all plugin in my Windows 7 machine… WARNING[24845][C-000000a6]: chan_sip.c:10487 process_sdp: Rejecting secure audio stream without encryption details: audio 52954 UDP/TLS/RTP/SAVPF 109 0 8 101
the same setup is running best for the google crome. plz give the solution to this problem…thank you.

Firefox only works with wss and need certificates to work.

thank you navaismo…can you tell me where i get the required documents to generate certificate for firefox.(i am using asterisk 11 on centos 6).

it required the webrtc2sip getway between the sipml5 browser based client and asterisk?
plz reply.

is certificate required is self signed or Signed(CA) certificate should you please explore.