There are variants of emergency radio which do have built in microphones and allow voice on 121.5. The use of the option is not encouraged, as it eats battery life. Some variants of 777 may have them fitted. Most modern units transmit location (GPS co-ordinates) on 406 MHz also, although some still don't - the odds are that anything fitted to a 777 will.
Typical units:-
http://www.transair.co.uk/sp+Kannad-...egra-ELTs+4010
http://www.sportys.com/pilotShop/product/16431
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Last edited by Genghis the Engineer; 17th Sep 2014 at 22:58.