ice attributes comes BEFORE any media declaration in firefox
i.e:
    v=0
    o=Mozilla-SIPUA-22.0 17330 0 IN IP4 0.0.0.0
    s=SIP Call
    t=0 0
    a=ice-ufrag:e456b676
    a=ice-pwd:b910fe1c321abf88cc6544094d8b85be
    a=fingerprint:sha-256 C6:71:E8:13:F2:18:87:AF:FA
    m=audio 44937 RTP/SAVPF 109 0 8 101
    ...
Only generate jingle media for effectively declared SDP ones