What to do if MMS on your unlocked Galaxy S8 Plus is not working

Many Android users have this mistaken notion that unlocked devices are no longer restricted in any way and can be used just like any other device in a new network. Unfortunately, that’s exactly the case, as what one user finds out below. Today’s #GalaxyS8Plus troubleshooting article talks about the basics about why MMS does not work on an unlocked Sprint device and what can be done about it.

Today’s problem:  What to do if MMS on your unlocked Galaxy S8 Plus is not working

Hello. I bought a Sprint S8 Plus off Craigslist and had Sprint unlock it, then switched to MetroPCS. The MMS never sends, I can’t get advanced messaging registered or activated and it just sucks so I wanted to flash to a MetroPCS firmware before switching to T-Mobile (and flashing a T-Mobile firmware). right before I was about to begin I had everything I needed downloaded but I still I didn’t feel like I knew enough and didn’t want to just blindly follow some random persons steps so I researched a little more and discovered the OTA I recently did could be a bricking machine. Is it possible to flash through different USA carrier firmware on a Sprint carrier phone without bricking? I don’t know if my phone is from USA or Canada or what but my software version is G955USQU2CRB9. Not sure what that restricts my abilities to on the January update but I’d like to know more before I attempt this. — Kris

Solution: Hi Kris. In general, flashing a different firmware (or operating system version) by a different carrier to a carrier-branded device may be possible but it can permanently cause a software problem. Flashing is just a term to denote the process of replacing the current firmware or ROM on a device with another firmware. When you flash a firmware, you are basically replacing the contents of your phone’s flash storage with that of another firmware version. Yes, it can be done in theory but if that firmware version is incompatible, it can cause serious a software issue. So, in your case, flashing a MetroPCS firmware to your Sprint S8 Plus may be done but you’ll soon find out that your S8 Plus will no longer boot up, or will simply fail to power back on. Needless to say, you can’t just replace the operating system of your Sprint S8 Plus with a different one. This should answer your question whether or not flashing your device with another carrier’s firmware will break your phone.

Carriers put restrictions on their devices to prevent their software from being tampered with. Firmware versions from carriers includes proprietary apps, interface enhancements and services that are only provided to carrier-branded devices. All of these are part of the entire security package that carriers put on their device to make them difficult to access from the outside.

What does “unlocking” mean?

Unlocking can mean a few different things in Android scene but in your case, we assume that it refers to network unlocking. Carrier-branded phones are originally built by Samsung for use by specific networks that order them. Since every carrier has their own network specifications and requirements, Samsung devices, even if they’re of the same line (Galaxy S8 or S8 Plus for instance) may differ in some hardware specifications. So, while you may have a Galaxy S8 Plus, it’s hardware is basically not exactly the same to that of a T-Mobile Galaxy S8 Plus. And since carrier-branded devices differ in hardware, their software or firmware are also different in some respects. This is the main reason why you can’t use T-Mobile’s firmware on a Sprint hardware. Putting in or flashing a T-Mobile firmware to a Sprint hardware can brick the device because the firmware is simply incompatible.

“Unlocking” your Sprint Galaxy S8 Plus does not mean the phone’s hardware has suddenly been changed to accept another firmware from a different carrier. Unlocking only alters network restrictions put by Sprint in order to make the device work with another compatible network. In some cases, unlocking may only allow certain network features to work. Unlocked Verizon devices, for example, may still not allow users to use MMS since data function is tightly tied to the device’s software architecture and this doesn’t get changed during unlocking. We think this is also the reason why your Sprint S8 Plus MMS functionality is wanting, even after the device has been network unlocked.


Sprint devices use CDMA technology so that makes them inherently difficult to use in other networks. While Sprint and Verizon have already made strides in minimizing compatibility issues with their network unlocked devices, we know for a fact that MMS functionality is still problematic. This is true for a lot of Samsung Galaxy devices from Sprint or Verizon. Unfortunately, software of CDMA devices are very difficult to modify and at this time, we’re not aware of a good way to make MMS work on an unlocked Sprint (CDMA device) S8 Plus.


If you can’t live without the normal MMS working on your phone, then you should consider replacing your S8 now. There’s no known way to bypass the network setup of your Sprint phone and allow it to use whatever carrier you’re in at this time.

However, if you only use MSM sparingly, then using other apps that allow enhanced messaging may help. There are many apps that you can use to allow you to send and receive photos and videos from the Play Store. Apps like Facebook Messenger, WhatsApp, Google Hangouts among others allow sending and receiving of multimedia. They also work on Android and iOS devices so friends who have non-Android phones can still send you photos and videos.


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Harvey is keen with mobile technology and loves writing about all things mobile. He is passionate in helping technology-challenged people by finding resolution to their issues.

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