asterisk users - Oct 2009 - Codecs with MixMonitor (,a) option

Hi all,

Another simple question: does it make sense to use the append option in 
MixMonitor (,a) when the codec is gsm? Or it works only when the codec 
is an uncompressed one like ulaw, alaw or slin?

Thanks,

-- 
Ing. Miguel Molina
Grupo de Tecnolog?a
Millenium Phone Center