[Verizon Samsung Galaxy S 4] MetaMav:
Hello Everyone!

This OP is meant to be a reference for anyone who may attempt to "unlock" their Verizon S4 so that they can use another carrier's SIM in their Verizon S4 (SCH-I545)

A few weeks ago, I naively followed a guide to unlock my S4 so that it could be used with other carrier's SIM cards. Example Guide (There are many of these throughout the web): http://xdaforums.com/showthread.php?t=2282683 - These guides are NOT meant to used on Verizon branded S4's.

For the record, I followed this guide in an attempt to change some of my network settings in order to get SMS working on a ROM, and did not realize the gravity of changing settings in the Service Mode Menu. To make a long story short, I changed the PERSO SHA256 status in the Service Mode menu (This menu is available on TW ROM's) and also attempted to restore the "Golden Backup" to the NV (Non-volatile memory - I believe). This inadvertently resulted in disabling calling and SMS on my phone. I later learned, and members like [MENTION=3940199]k1mu[/MENTION] have talked of this before:

Verizon S4's DO NOT NEED TO BE UNLOCKED

(and already have the PERSO SHA256 status set to "OFF" anyways.)

Our S4's are already capable of connecting to GSM, LTE, CDMA, and other some other network types for different carriers. If you decide to change your carrier to AT&T or Straight Talk, you can do so by changing out the SIM, changing your Network Mode, and setting up new APN's (all of which should be possible on a stock ROM). Although, I understand there are still certain limitations on our S4 with specific bands and network types that may not result in the most ideal performance on another carrier's network. There are also guides and threads throughout the forum that discuss different advanced settings and modifications to achieve certain capabilities on other carriers networks with our phones.

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The following information is in reference to MDK users. However, if you are on a different bootloader, Please read the end of this fix for a possible solution.

For those (MDK users) who have attempted to "unlock" their Verizon S4's and are having issues with SMS, Data, or Calling:

There is no way, that I determined, to reset the setting in the Service Mode menu to restore SMS and calling. I was able to change a lot of settings like network bands and data settings, but nothing to remedy SMS and calling. I even went to a Verizon retailer and got a new SIM card (which somehow restored SMS - depending on different Service Mode settings, ROM, and modem). I think Service Mode settings have an affect on both the phone's internal settings, as well as on the SIM card.

It took me many days, a lot of research, a lot of experimentation with Service Mode settings, and getting a new Verizon SIM to stumble on a solution to my issues. My solution arose form this post by [MENTION=1501413]colton22[/MENTION] http://xdaforums.com/showthread.php?t=2650296.

This is how I solved the issues:

I know it may seem obvious to ODIN back to stock, but that is not what fixed the issue. I tried that multiple times, tried many different modems, and tried many different network settings. However, the key to this is the Factory Reset via the touchwiz menu. I wiped my phone dozens of times, but it required the stock Verizon ROM factory reset option in order to regain full functionality.

This leads me to a possible fix for non-MDK users:

Thanks for your time! If you have any comments, or if you believe I need to make any corrections to the OP, please let me know.