QA have detected an issue when using Firefox as the WebRTC client and receiving calls. NOTE this does not affect outbound calls, only inbound calls. Inbound calls will establish but media between the parties is missing.
If you are running FCSDK version earlier than 3.0.1 (e.g. 2.8.*, 2.16.*) then inbound calls will be affected with FF 49.
FF 49 is currently scheduled for delivery on the 13th September 2016.
FF 49 features improvements their DTLS library which will have interop issues with older versions of Cafex Media Brokers DTLS stack.
Upgrade to FCSDK 3.0.1 or later.
If you have any queries about this behaviour or need to request access to the lastest versions of Cafex software please contact firstname.lastname@example.org.