[Sprint Samsung Galaxy S III] devastatorx:
Hey just thought I'd chime in here, as I was having major issues with data dying constantly out of nowhere and mms wasn't working. Just picked up an S3 two days ago and flashed this rom (definitely not a mistake, I'm loving everything about it, smooth, fast, great battery life). Though my data connection was constantly dying. After reading..pretty much the entire thread, decided to try a few different suggestions to get it fixed. For those having the same issue, here is what I did:

1) Flashed the TWRP open recovery after reading that it was recommended over CWM. TWRP can be found here. I flashed using the dd method, instructions are on the site if needed.

2) Backup with titanium/mybackup/whatevs (apps, app data, settings)

3) Boot to recovery and do a full nandroid backup (just in case and a good habit to make)

4) Do a factory reset (wipe data and cache) This is very important! If you don't do this, the next step will have you stuck in a bootloop, and the only way around it is to boot to download mode and odin flash any custom recovery to wipe data. So, just do it now and avoid the hassle.

5) Per SaddieNibblesworth I flashed the stock JB rom with root injected which can be found here This will also flash the newest LJ7 modem

6) After flashing via odin let it reboot into the rom.

7) Once fully in the rom, do a PRL update and then Profile update.

8) Re-flash TWRP recovery using the dd method.

9) Reboot to recovery

(optional) do a nandroid backup of the stock rooted JB rom (you know...so you dont have to flash it with odin again. And, if something goes awry, you'll have this to fall back on. Just a suggestion)

10) Factory reset (wipe data and cache) 3 times

11) Wipe dalvik cache

12) Flash ParanoidAndroid

13) Flash Gapps

14) Wipe dalvik and cache again (for good measure)

15) Reboot into rom

16) Restore your titanium/mybackup/whatevs backup you made

Hopefully after all of this, enjoy a non dying data connection. I can't yet comment on mms as I havent attempted to send, nor have I recieved one. I'll report back on this one.

Now, as all things go with fixes like this, YMMV. If it doesn't work, you may try searching this thread (specifically SaddieNibblesworth's posts and try flashing a different radio (radios here) or try a different PRL.

Good Luck, and hope it works out!

-devx

EDIT: MMS is still not working, I really loathe having to use a third party app for this, can anyone throw some suggestions my way as to how they have theirs working? Thanks in advance

EDIT Again: Grabbed a logcat of the failed mms retrieval, maybe this will help:

11-25 10:51:44.521 8869 9181 E Mms:transaction: Url: http://mms.sprintpcs.com:80/ (i removed url before posting)

11-25 10:51:44.521 8869 9181 E Mms:transaction: HTTP error: Forbidden

11-25 10:51:44.521 8869 9181 E RetrieveTransaction: java.io.IOException: HTTP error: Forbidden

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at com.android.mms.transaction.HttpUtils.handleHttpConnectionException(HttpUtils.java:299)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at com.android.mms.transaction.HttpUtils.httpConnection(HttpUtils.java:285)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at com.android.mms.transaction.Transaction.getPdu(Transaction.java:196)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at com.android.mms.transaction.RetrieveTransaction.run(RetrieveTransaction.java:136)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at java.lang.Thread.run(Thread.java:856)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction: Caused by: java.io.IOException: HTTP error: Forbidden

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	at com.android.mms.transaction.HttpUtils.httpConnection(HttpUtils.java:208)

11-25 10:51:44.521 8869 9181 E RetrieveTransaction:	... 3 more

11-25 10:51:44.521 8869 9181 E RetrieveTransaction: Retrieval failed.