[AT&T Samsung Galaxy S 4 General] dcoke:
This is using Grgsiocl's modified SecPhone.apk. It allows you to record calls from your phone while also changing your old phone to the international version (Black-ish instead of the white of the US models). He provided a zip, which I was afraid of flashing since he wrote the code for the i9500 and not the US variants. Oh, by the way this is for Deodexed roms, so make sure you have one of those. That's kind of important. Also with that said, you need to be rooted, but if you're already Deodexed then I assume you're already rooted.

So here's what I did:

1) First download his zip file: http://www.mediafire.com/?13pezaa8reobrno

2) Then I opened up his zip and went hunting for the apk (it's in the Apps folder within the System folder)

3) Copy it to your phone or sd card. I keep all of mine in a folder labeled Roms where I put Roms and other flashable mods in. DO NOT RENAME IT. ***Remember where you put the file since you'll be using it shortly. Write it down if you have to.***

4) Once that is done put your sd card back into your phone if out or unplug your phone from your computer

5) Open a root explorer, there are a lot of options on the Play store. I use Rom Toolbox, others use ES File Explorer and what not.

6) In your root explorer of choice make sure you're in the root of your device and not in an internal or external memory area.

7) Locate the "System" folder and open it

8) Then navigate to "Apps"

9) Look for the app called "SecPhone.apk" (sometimes they'll leave out the ".apk" and just have the app name depending on what file explorer app you're using.

10) Copy that application (some require you to press and hold down on the app in order for the explorer to allow you to copy)

11) Copy that application to your internal or external memory card anywhere other than where you have the modified "SecPhone.apk" file so it doesn't override it. There, you just backed it up if the new APK doesn't work for you. You want to copy it and not move it since if you move a crucial system file it can create a rather annoying "error" loop. I've had it happen to me multiple times and the only way to fix it is usually reflashing a rom. Very annoying.

12) Now locate the modified "SecPhone.apk" and also get to where you can copy it.

13) Once you have it selected and ready to copy it you are going to copy it in the root\system\app folder and when prompted you will override the one that is currently there.

14) Once the modified APK is in place you'll need to reboot into recovery.

15) In recovery you will do three things: wipe Dalvik Cache, Fix Permissions and reboot your phone. If you don't do this the app won't work after 1 use, speaking from experience.

16) Once your phone is rebooted you can test out your new and modified SecPhone.apk app and have fun recording calls.

!!!!!!REMEMBER RECORDING CALLS ISN'T LEGAL IN ALL STATES AND IT IS PROPER ETIQUETTE TO LET THE OTHER PERSON KNOW THAT THE CALL MAY BE RECORDED. SO ANY NEGATIVE OUTCOME (LEGAL OR OTHERWISE) THAT YOU RECEIVE FROM THIS ISN'T MY FAULT NOR GRGSIOCL'S!!!!!!

It saves the calls to your internal memory in a folder called "Sounds".

-Enjoy

Many thanks to Grgsiocl and his work.

The original thread is: http://xdaforums.com/showthread.php?t=2268146