This will show you how to prepare your Samsung SGH-T739 Katalyst to permanently accept non-T-Mobile SIM cards. Although the Katalyst is best used on T-Mobile because of the UMA feature (Unlicensed Mobile Access) sometimes using other carriers is unavoidable.

Photos of the same handset taken a minute apart after going through
the exact unlocking process described in this guide. AT&T and
T-Mobile on the same handset if you need it? No problem! This is
extra valuable for the Katalyst because of it being a QuadBand phone.
It will work where AT&T operates on 850 MHz.

Is This Guide Helpful?

Think about that question as you read this guide. If you believe you would be able to make use of this information if you had a locked Katalyst in front of you as you read this consider giving this a guide a positive vote. I provide help to those who have asked for it to get them through the process.

I developed this guide through recording the steps I took to unlock several Katalyst devices. Recently, after not touching a Katalyst for a month or two I unlocked one using this guide exclusively to ensure I hadn't forgotten anything. As a result this guide received some revising. I hope it is now more comprehensive, easier to understand and more user friendly. If you find it unclearly written or just flat incorrect please contact me and let me know. I'm very good at taking informed criticism. So, have at it! Please note that the three negative votes are after ~3500 views. They came with no request for assistance. I can only assume the negative votes were from disgruntled merchants from the right hand column.

Now - Let's Get It ON!

A. Insert a T-Mobile US SIM. Go to Settings > Security > Change Password. Set password to 00000000 (eight zeroes) if you have changed it from the default password.  The reason for this is you are going to be accessing the service areas of the phone. Making adjustments in those areas requires a password as part of the code string you enter.

B. Turn on phone with full battery and non-T-Mobile SIM in place.

Allow phone to completely boot up to Wrong Card screen.

C. Enter from Wrong Card Screen

 *#7465625# to bring up the Interrogate screen to confirm lock status.

D. Scroll through Interrogate Screen. The background will be different but it will look pretty much like the image below.

1.  Network lock - Active (this is the one you'll be deactivating)
2.  Subset lock - inactive
3.  SP lock - inactive
4.  CP lock - inactive
5.  SIM Card lock - inactive
6.  Activa lock - inactive
7.  Auto network lock - inactive
8.  Auto subset lock - inactive
9.  Auto SP lock - inactive
10. Auto CP lock - inactive
11. Auto SIM Card lock - inactive
12. Phone lock - inactive

E. Push "C" button under navigation button to clear Interrogate screen back to Wrong Card screen or use the "Back" soft key. Either one will work.

F. You are back to the "Wrong Card Screen. Take a good look. This may be the last time you see this screen. From the Wrong Card  screen enter the following:

*7465625*638*00000000*00000000#  Those are two series of eight zeros. The phone will not show the zeros but will show dashes in their place.

Phone may make a small tone and at the bottom of the screen it will read "Network Personalized" or perhaps "Network Already Personalized". If you do this with no SIM in place you will receive the "No Lock Code In SIM" message. Phone will not unlock if no SIM is in place. I know, I tried it because I was asked about that. Now at this point your phone is temporarily able to use a "foreign" SIM. But if you were to remove the battery it would relock. To make it permanent continue to the following steps.

G. Now input the following from whatever screen shows up:

#7465625*638*00000000# (again this is a series of eight zeros)

Phone may make small tone and will read "Network Lock Deactivated"

H. Turn off phone and allow it to reboot.
J. Enter from Standby Screen

 *#7465625# to bring up Interrogate Screen and confirm lock removal status

K. Scroll through Interrogate Screen

1.  Network lock - inactive (note that this lock is now inactive)
2.  Subset lock - inactive
3.  SP lock - inactive
4.  CP lock - inactive
5.  SIM Card lock - inactive
6.  Activa lock - inactive
7.  Auto network lock - inactive
8.  Auto subset lock - inactive
9.  Auto SP lock - inactive
10. Auto CP lock - inactive
11. Auto SIM Card lock - inactive
12. Phone lock - inactive

That's it.  Your Katalyst is ready to accept SIM cards from just about any GSM mobile telephone service provider in the world.

I was recently asked about clearing and resetting the phone. This is a truly easy task once you know how. From the standby screen enter:

*2767*3855#

You had better mean it. Once you enter the # there is no turning back. Your Katalyst will be returned to its factory condition. Except if you unlocked it using the instructions above - it will still be unlocked. Thank you Margie for your request for this information. Always glad to increase my knowledge and share it when I can.

Another question has come in about removing the T-Zones and other T-Mobile goodies.

This is done in a p[rocess called de-branding. I cover the pros and cons of this in a different guide. Everyone who has a Katalyst knows how lame the Bluetooth function is. It is limited by the T-Mobile firmware. Unlocking the Katalyst will not change that. It simply makes it possible to use the phone on a different network with the same firmware.

© 2008, 2009 by Robert Chambers All Rights Reserved