There were a lot of complaints related to the inability of the Samsung Galaxy S4 to be used cross-carrier. It is because some wireless companies wanted their devices locked so that they cannot be used under different service provider. Others simply want even more revenue by selling their network unlock key or “Network Control Key.”
Basically, when your Samsung Galaxy S4 is locked to a specific network, there are two things you could do:
Purchase Network Control Key from your provider. Transferring from one network to another is easy, it’s their processes that often piss you off. But basically, what you need to do is contact the carrier you wish to use and buy Network Control Key. More often, this key is needed for GSM phone so you would need to buy a SIM card together with it. Once you got the network unlock key, here’s what you need to do:
Step 1: Turn the WiFi Off.
Step 2: Power down your phone.
Step 3: Remove the SIM card and insert the new SIM card.
Step 4: Turn your phone on.
Step 5: When prompted, enter the code. More often, it is an 8-digit code.
You would know if the process was successful because you would see a dialog box containing “Code Accepted” or “Network Lock Successful” message.
However, in case you will not be prompted after powering on your phone, follow these steps:
Step 1: Launch the Phone app.
Step 2: Dial this code: #7465625*638*#
Step 3: Enter the 8-digit unlock code.
Flash third-party custom ROMs. Network-locked phones are using firmware or application from the provider, thus, it is firmware-specific. One way to unlock these phones is to flash custom ROMs, although there are also dangers that come with it. Custom firmware like CyanogenMod and SlimBean are always unlocked.
Some providers don’t offer unlock codes to their customers so this procedure will come in handy. It is also advisable that if you purchase smartphones like the Samsung Galaxy S4, buy the international variant.
Tell us your phone problems
The solutions we provided here are based on reports and testimonies from owners who have encountered these problems. I also ask my XDA developer friends regarding some of the problems. Now if you have other problems or questions with your smartphone that you want answered, don’t hesitate to send us email at email@example.com.
We don’t guarantee a reply to all emails because we receive hundreds of them daily, but rest assured your email messages will be read by me. But I urge you to provide as much details as possible so I could easily find references and compare your problems with reports from other owners. If your problem is as common as others, there could already be solutions that exist and I would surely point you to them. Screenshots often help so attach one if you can.