MES to Satellite decoding and A5-1-GMR decrypt

Dear all, Right now I am studing on osmGMR code and try to understand how it works. From the code my understanding and concerns are as below: 1.  It looks like osmoGMR gmr1_rx only analyze and decode downlink(Satellite to MES) messages and data,  am I right?  If there any similar application that can decode both downlink and uplink(MES to Satellite)? Or osmoGMR needs input to implement downlink decode? 2.  A plaintext-decrypt is mentioned in osmoGMR wiki but no detail about how to implement it.   Is there a opensource code for A5-1-GMR? Or any other clue that can understand how plaintext decrypt  A5-1-GMR? Does osmoGMR need input to implemen it? Best Regards, Tiger