This Video is for iPhone 3gS users who depend on Ultrasn0w to Unlock their devices. Follow this correctly to have your iPhone 3gS Jailbroken and Unlocked successfully.
NOTE: If you are getting error 3194/3195 while updating then to solve this follow these instructions www.evasionjailbreak.org/fix-itunes-error-3194-during-ios-update/
Just takes a minute or two. Then you must REBOOT your Computer.
Step 1: Update your iPhone 3gS via iTunes on your computer. Download iOS 6.1.6 from here: appldnld.apple.com/iOS6.1/091-3457.20140221.Btt3e/iPhone2,1_6.1.6_10B500_Restore.ipsw
It will be updated to latest iOS 6.1.6 (Final Official version for iPhone 3gS)
Step 2: After the update if you are on an Unofficial Carrier or have no Sim Card then you will be stuck on Activation Screen. So run Redsn0w to bypass this Activation Screen. In Redsn0w BROWSE iOS 6.0 VERSION for iPhone 3gs (NOT iOS 6.1.6) Download iOS 6.0 here: appldnld.apple.com/iOS6/Restore/041-7173.20120919.sDDMh/iPhone2,1_6.0_10A403_Restore.ipsw
Step 3: Once you have bypassed Activation Screen, you will NOT see Cydia on your iPhone. You need to turn it off and run Redsn0w again with 'Just Boot' option exactly as shown in the video.
Step 4: After 'Just Boot' You will see Cydia. Launch it and let it load its sources completely. Ignore Cydia Updates temporarily exactly as shown in the video and search for "P0sixpwn" (O is 0 here). Install it and this will make your Jailbreak Untethered. Now install all Updates by going to 'Changes' tab in Cydia. Reboot. Please NOTE that if your iPhone is Old Bootrom then you don't need to install P0sixpwn. Your Jailbreak is already Untethered.
Step 5: Last and final step is to install Ultrasn0w. Now your iPhone will be fully Unlocked and you will have an Untether Jailbreak on iOS 6.1.6
((Not required- But you can find all iOS versions to download here www.iclarified.com/750
a) Keep in mind to Browse iOS 6.0 version in Redsn0w.
b) If your iPhone is updated to iOS 6.1.6 and you do not know what baseband it has then simply open Redsn0w on your computer and it will tell you your iPhone baseband (also shown in the video). So choose wisely what to do.
c) When selecting 'Just Boot' option, also browse iOS 6.0 first in 'Select IPSW' option and then choose Just Boot option. Also make very sure to power down your iPhone completely i.e, Slide to Power off.
d) If Redsn0w keeps failing to Jailbreak your iPhone 3gS then Restart your computer and try again.
e) Remember to turn off iPhone completely before doing any DFU mode.
f) If iPhone gets stuck on reboot then Hold Home and Power buttons together for 15 seconds, it will reboot normally. If that don't help then try this out www.iphonehacks.com/2013/02/fix-endless-reboot-loop-problem-jailbroken-iphone-ipad-ipod-touch.html
g) After installing Ultrasn0w you still don't get any service, then try to install iPad baseband again using Redsn0w's "install iPad Baseband" option. Do this even if you already have iPad baseband 06.15.00 on your iPhone. Or if you already have 06.15.00 baseband then downgrade it to 05.13.04 by choosing Redsnow's 'Downgrade iPad baseband' option.
h) Issues with SMS after Jailbreaking: Try 'HandcentSMS' Tweak from Cydia.
Feel free to leave a comment or ask me a private message as you like. Good luck !!