Last week I documented how to get a Samsung Galaxy S4 L720 (Sprint) phone working on Domestic GMS networks. After a week of using the Google Play Edition ROM for the Samsung Galaxy S4 L720 (Sprint) phone, I can report that I am quite pleased with it.

Since then I have found out that I can indeed install CM 12.1 based ROMs on this device and have it use the GSM networks by default. I was looking into how to make the change in the phone and found a post on XDA that gave me the final trick. Before this I had tried to use the dialer ( #*#*4636*#*# ) to get to the test screen and make the change, but that would never stick. I tried making the change in the network settings from LTE to GSM, but again it would not work. The phone always ended up back on Sprint.

The other feature that I desired was to be able to use the F2FS filesystem for the cache and data partitions. F2FS is a fast filesystem that was built for Flash storage and is much more efficient than ext4. The only issue is that the Google Play Edition ROM doesn’t support F2FS yet. To get the best of both worlds I had to change to a unified CM 12.1 ROM for jflte, with the added bonus of moving to android 5.1.1, and change a setting in the /META-INF/com/google/android/updater-script so that the L720 uses the GSM network instead of CDMA.

I am also running the Hulk Kernel. This gives me F2FS support and some additional features that are useful to me. I have found it quite stable and it can be installed for TouchWiz systems also which is a huge benefit to anyone using that system.

I would imagine that any jflte unified ROM would work, I have yet to try it. To also get the F2FS system working, I updated to TWRP 2.8.6.0 as per the instructions in the AntaresOne CM12.1 forum. This ROM is working well for me, tho I did experience an error with google services that is preventing the device from syncing mail and calender items right now. I will need to re-flash things and see if I can get it sorted out. The last thing I need to do is copy all the files from the /data partition to the external SD card and then reformat it as F2FS.

Once this is done, I will document the final results.

I hope these notes are a help to someone else and it makes their life just a little easier. Happy Flashing.