play the voice signal ?

hi, I am using "fcdp-tetra_demod.py" with my funcube dongle and i can decode datas. The networks in my place are unencrypted. I saw on the "Dieter Spaar's blog" : "I also implemented some proof of concept code which allows decoding speech traffic and converting it to raw audio using the TETRA reference codec. Please note that this cannot be used to listen to encrypted TETRA traffic, it only works if no encryption is used. " Is it possible to release some part of the code necessary to decode Tetra voice or give some explaination of Gsmtap usage ? thanks for answer