The more common name is modem. When I started flashing Cyanogenmod nightlies, I installed GetRIL. It was supposed to download the correct versions to match modem driver with the Radio Interface Layer (RIL). It never did. Strangely I never suffer any negative side other than a time when I was in Korea.

Due to RIL locks and other issues, CM started moving towards their own OpenRIL, and that made modem drivers truly plug and play. Well sort of as there were no reports of anyone zapping their phone with the modem drivers.

I have decided to try to get my modem driver back to original Samsung version. In the course of doing so, I came across multiple versions. So which one to use?

I tested out various region modems by doing an overnight power drain test. After all if it is sitting pretty doing nothing, at no other time, the power drain can be better, only worse. XX is for Europe, DX is for Asia. The phone is full charged before I sleep and allowed to discharge overnight. The results were interesting.

Even though XX region modem is well not for this region, the power drain test turned out quite well. Not by a wide margin, but good enough to be considered as the download performance was quite good.  In the end all this will come to nothing, if your build does include the Google Services Framework bug fix.

RIL link  CM introduces OpenRIL link