The Apple iOS is designed in such a way that all applications with the push facility should request the Apple APNS servers for a token that identifies the device. The application requesting APNS token will be jammed in unlocked iPhone models. So they usually not support push notifications. Unlocked models have less battery life and produce more heat than the officially activated models. Many people who unlocked their iPhone 3G and 3G S with the recent Redsn0w 0.9.6 b5 and Ultrasnow 1.2 were reported to have these problems. Thanks to Sam Bingner, from bingner.com. He developed a Cydia repository called SAM that can officially activate iPhone 3G and 3G S on iOS 4.2.1 without the original SIM card or hactivation.
The iPhone-dev team released a new Redsn0w 0.9.6b6 to make it easy for the users to deploy and test the SAM features. So when you use SAM and Redsn0w 0.9.6 b6, you can officially unlock and activate your iPhone 3G or iPhone 3G S and get the push notification working and improve battery life.
Official activation for iPhone 3G or 3GS on iOS 4.2.1 with SAM and Redsn0w 0.9.6 b6:
First jailbreak iPhone 3G or 3GS (iOS 4.2.1) with Redsn0w 0.9.6b6. Redsn0w 0.9.6 b5 jailbreak procedure (old) is given here.
Open Cydia from your jailbroken iPhone 3G or iPhone 3G S.
Now add a new Cydia repository URL as http://repo.bingner.com and save.
Go back and from manage section, click on Binger.
Now install SAM and SAMPrefs from the sources list.
Open Redsn0w 0.9.6 b6 again and in the second step, use the deactivate option as shown above.
Go to the settings>SAM and click deactivate.
Connect your iPhone 3G or 3G S to iTunes and activate it.
We will get a a better battery life and push notifications working as the process is not a hactivation.