I’ve taken over this thread, and I’m going to try to keep things a bit more organized.
First, you need to identify your model; This is fairly simple, you just need to either know what carrier it came from, or have the box it came in. If your phone came from AT&T, it’s an I747U. If your phone is from a Canadian carrier such as Telus, Rogers, Bell, Fido, Koodo, Sasktel, or MTS, you probably have an I747M. If you’re unsure, look on the bottom of the box it came in; Canadian models should all say SGH-I747M, while I believe AT&T models only say SGH-I747. Please let me know if yours says something different.
Things you’ll need:
- Root (Technically you don't.)
- Custom recovery (See my signature for help with this!)
- The ability to click “Search” when you need help
- A basic ability to read
- And most importantly, a GALAXY S3 I747!
All modems posted in this thread will be flashable ZIPs, usable in either ClockworkMod or TWRP.
How to flash:
1. Choose a firmware from below and download it to your device’s SD card or internal storage.
2. Reboot into your custom recovery.
3. Select the option to “Install” (same as installing a ROM) and locate the ZIP from step 1.
4. After flashing, clearing your cache and dalvik cache is strongly recommended.
5. Reboot and enjoy!
Modems are listed in the following format:
Version: Download Link - Build Date
AT&T and other non-M devices.
I747UCLEM: modem_CWM_I747UCLEM.zip - 19.06 MB - May 22nd, 2012 (original shipped)
I747UCLG1: modem_CWM_I747UCLG1.zip - 19.06 MB - July 1st, 2012
I747UCLH1: modem_CWM_I747UCLH1.zip - 19.40 MB - August 1st, 2012
I747UCLH9: modem_CWM_I747UCLH9.zip - 18.90 MB - August 9th, 2012
I747UCLI5: modem_CWM_I747UCLI5.zip - 19.51 MB - September 5th, 2012
I747UCDLK3: modem_CWM_I747UCDLK3.zip - 18.42 MB - November 3rd, 2012
I747UCDMG2: modem_CWM_I747UCDMG2.zip - 19.01 MB - July 2nd, 2013
I747UCUEMJB: modem_CWM_I747UCUEMJB.zip - 19.15 MB - October 11, 2013
Telus, Rogers, Bell, Fido, Koodo, Sasktel, MTS, and other M devices.
I747MVLLE8: modem_CWM_I747MVLLE8.zip - 19.42 MB - May 8th, 2012 (original shipped)
I747MLALH1: modem_CWM_I747MLALH1.zip - 19.62 MB - August 1st, 2012
I747MVLLH1: modem_CWM_I747MVLLH1.zip - 19.46 MB - August 1st, 2012
I747MUMALJ1: modem_CWM_I747MUMALJ1.zip - 19.48 MB - October 1st, 2012
I747MUMBLK3: modem_CWM_I747MUMBLK3.zip - 18.97 MB - November 3rd, 2012
I747MVLDLK4: modem_CWM_I747MVLDLK4.zip - 18.92 MB - November 4th, 2012
I747MUMBLL1: modem_CWM_I747MUMBLL1.zip - 18.97 MB - December 1st, 2012
I747MVLDMF1: modem_CWM_I747MVLDMF1.zip - 18.99 MB - June 1st, 2013
I747MVLUEMK5: modem_CWM_I747MVLUEMK5.zip - 19.17 MB - November 5th, 2013
I747MVLUEND2: modem_CWM_I747MVLUEND2.zip - 18.79 MB - April 2nd, 2014
I747MUMUEND3: modem_CWM_I747MUMUEND3.zip - 18.80 MB - April 3rd, 2014
Check my Dropbox if d-h.st is giving you issues.
Call Display w/ Name not working after updating? Check this post. (Note: This doesn't affect names saved in your phone, only names that are obtained via your carrier's "Call Display Name" feature.)
Q: What is a modem, anyway?
A: The modem is the chip inside your phone that controls the connection to the cellular towers. This is a collection of different firmware versions for that chip.
A: Firmware is a type of software that directly controls how a piece of hardware operates. It’s a bit like a driver on your computer. (Yes, I’ve oversimplified this. Wikipedia can tell you more.)
Q: Which one do I use?
A: Make sure you’re using one for the correct model; Beyond that, it’s completely up to you. Results will vary from location-to-location, and even device-to-device. Try them yourself and see which one works best for you. (Note: Some people say that their reception gets better over time if they let the firmware “settle”. This doesn't make much sense, as the firmware doesn’t work like that, but feel free to try anyway.)
Q: I flashed the wrong model’s firmware, am I screwed?
A: Probably not. Just reflash the correct firmware and clear your dalvik cache, and you’ll probably be back in business. In worst-case situations, I’ve seen a phone require a full ROM reinstall including wiping /data, but that’s the price you pay for not reading the directions.
Q: Can I install this if I am not rooted?
A: Technically, root is not required for this, but how do you plan on getting the custom recovery on there without root?
Q: Will this give me LTE?
A: If you’re not getting LTE now, you probably won’t get any different results with a different firmware. Check your carrier’s network map to ensure you have LTE coverage in your area.
Q: My data/voice/SMS performance is much worse with X firmware…
A: Try another! Keep track of which ones you’ve tried and post back here with your results. It’s even more helpful if you give us your general location along with your results.
Q: My phone says “4G”, but my speeds are terrible… Will a different modem firmware fix this?
Short A: Maybe, but probably not.
Long A: Are you still on a carrier-built ROM? Carrier ROMs “lie” to you and label HSPA (which is a 3G technology) with a “4G” badge. This was a marketing ploy long before LTE ever existed. Now that everyone’s used to being on “4G” networks, they needed to come up with a way to differentiate LTE as something “new”, so they kept “4G” as the label for HSPA, and have added the “4G LTE” label for when you’re actually getting real 4G service. Most custom ROMs fix this, and properly tell you if you’re getting “3G”, “H”(for HSPA), “H+” (for HSDPA or HSPA-DC), or “4G” (for LTE). Flashing the modem firmware can't fix this specific problem.