Hey all, creating a new thread on this as it has blew up in the past couple of days and got the original thread all sorts of off topic. I am sharing my findings here in hopes that it will help others get Lollipop running on their StraightTalk S3 (or KK roms based off of CM after the 9/7 updates).
First a little history. Before the unified roms I was running d2vzw LiquidSmooth without any issue, then in late Feburary (2/26) the S3Unified rom was built, putting the correct rilblobs in /system/lib upon boot (if I am reading the code right that is). This was when I noticed that the Unified rom broke the S3 ST phone (no data), so I spent a couple of days researching and learning how to build roms and came up with this commit to LiquidSmooth, I noticed a few days later that it was pulled into the CM source, so all roms were back to working with our phone. I also vaguely remember something with rilblobs needing reverted around this time. So at this time, everything was working, up until the 9/7 CM updates where the rilblobs were once again changed. I worked with one of the CM devs (invisablek) on this issue and we were never really able to figure out what the issue was, the radio was throwing all sorts of odd error messages and would never connect. During that time there was enough of a change that even the old rilblobs wouldn't work (spent about a week worth of evenings trying to no avail). So I ended up giving up until 5.0 hit.
Yesterday I came across a d2lte CM12 build! Flashed it and was quite impressed to see everything working except mobile (both calling and data). In that thread I ran across the first linked thread here and seen that inserting a sim card seemed to work, so I hit up a coworker (on AT&T) and asked him if I could borrow his sim. He agreed, so I pulled the battery, popped in the sim and was AMAZED to see mobile working again, did a test call, browsed on 3g, and everything was working quite well. Got home last night and found an old (deactivated) sim card in my basement, popped it and have ran CM12 all day. Hooked it up to the bluetooth head unit in the car, setup a second account for my son, taken a few pictures, everything seems to be working fine.
One thing that has bugged me for a while (which I rarely use) was that MMS stopped working (not sure exactly when, but I'd guess back on 2/26), so I spent some time today pulling apart files, modifying things, and really haven't gained much (at least for the stock MMS). I did get hangouts working as MMS by adding an apn (Hangouts -> Settings -> SMS -> SMS Enabled, then scroll to the bottom and click on Access Point Names, Add one with the following settings Name Verizon Internet, MMSC http://mms.vtext.com/servlets/mms MMS proxy and port are blank, MCC 311 and MNC 480 ). I haven't completely given up on the stock messenger app, but I am done with it tonight.
Here are the things I have done so far:
Modified build prop to include TracFone Settings
added apns-conf.xml to /system/etc (and modified it a few times)
a few different apps to change APN settings (seems like all of them fail)
If anyone wants, my wifes S3 hasn't been touched, so I can get any of the 4.1.2 rom files from it if its helpful to anyone. I did run across this but I haven't had time to try it yet, and I ran across another page where they modified the messenger.apk and changed some of the apn settings in there (definitely interested in looking into this).
Also to clarify, what I believe is happening here with the sim card is this, Verizon updated their RIL's to require a SIM (make sense since they use 4G), and if it doesn't find one it shuts down the radio in the phone, so until ST updates their RIL's, we will probably be stuck. It might be interesting to see if some could 'emulate' having a sim card in using a 3rd party app (its well beyond my programming capabilities I am afraid).
Sorry for my rambling, but I hope this has been helpful to someone, and I am hopeful that this will take off and let the ROOTING thread go back to helping people root . Please post any other SCH-968C findings you have here, maybe we can get a good collection of information in one place.