See slide 30 on this Neo900 presentation: http://neo900.org/stuff/ohsw2014/ohsw2014.pdf http://neo900.org/stuff/ohsw2014/ohsw2014.pdf Also see the various kill

See slide 30 on this Neo900 presentation: http://neo900.org/stuff/ohsw2014/ohsw2014.pdf http://neo900.org/stuff/ohsw2014/ohsw2014.pdf Also see the various kill switches on the block diagram (GPS kill, modem monitor, mic not directly attached to modem (so you could probably send fake audio/silence),etc: http://neo900.org/stuff/block-diagrams/neo900/neo900.html http://neo900.org/stuff/block-diagrams/neo900/neo900.html See slides 16 through 23 here for some details on the modem/audio monitoring/separation: http://neo900.org/stuff/cccamp15/ccc2015talk/talk.pdf http://neo900.org/stuff/cccamp15/ccc2015talk/talk.pdf Would this meet some of your criteria? If there is something missing you can discuss with the people involved (on IRC usually): http://neo900.org/contact http://neo900.org/contact