Contrary to what almost every T-Mobile representative will tell you, you do not need the data plan for the G1 to function. I do not have a data plan and have a rooted G1 that I use everyday. The only downside is that MMS and IM will not work without a data plan. SMS will still work. IM will still work if you have Wifi. IM only works with a data plan because it needs an internet connection to sign on though the default IM app will count a message as a text.

First, You must have either RC29 or earlier, or a custom ROM (basically anything with root access). It won’t work with any official releases (RC30 or later), sorry. If you don’t know for sure what version you have, but you know you haven’t installed a modified RC30 build, then the easiest way to check is to reboot the phone, and once it starts up and is showing the “click the android to begin” screen, or the “no sim card” screen, then type the following on the phone keyboard:

<enter>reboot<enter>

If it reboots, then you have RC29 or ealier. Otherwise you have RC30.

Second, you must have adb installed on your computer, and have the USB drivers installed, or at least ready to install when it asks for the driver when you connect the G1. See this page for details on how to get adb working: http://code.google.com/android/intro…devicehardware

Third, you must have a wifi network that you can connect to.

There are too many possibilities to write specific step-by-step instructions for every case. So I will give an overview of the process instead. If someone else wants to write some specific instructions, that would be welcome

————————————
<<<NO SIM CARD>>>

When you start up the phone without a sim card, it goes into a locked screen that says “no sim card found”, and you can’t even get into the registration app. So the first step is to get around that screen. You have to connect to your phone with adb shell and get root access, and then type the following command:
sqlite3 /data/data/com.android.providers.settings/databases/settings.db “INSERT INTO system (name, value) VALUES (’device_provisioned’, 1);”

And then reboot the phone. When it starts up again it will go into the registration screen instead of the locked “no sim card” screen.

This assumes that you have the sqlite3 binary on your phone. This binary is provided in RC30 v1.2. Alternatively, you could manually copy the binary to your phone with adb push, or put it on the sdcard and copy it to your phone. I can post a copy of just the sqlite3 binary if needed.
————————————
<<<NO DATA PLAN>>>

If you do not have a data plan, follow this portion. It enables Wifi before the registration step begins so you can register over Wifi instead of using a data plan.

The second step is to enable and configure wifi, so that the registration process can connect to the google servers. In an adb shell session, type the following command:

am start -a android.intent.action.MAIN -n com.android.settings/.Settings

This doesn’t have to have root access to work. It works fine with the “shell” user that adb on non-modded phones runs as. However, it still requires RC29 in order to enable ADB.

That command will bring up the settings page on your phone. From there, you can enable wifi and connect to your wifi network, and then proceed with registration as per normal

————

A few tips and tricks:

- If you have an official RC29 or lower phone, type the following command on the phone keyboard to enable adb:
<enter>setprop persist.service.adb.enable 1<enter>

- If you need to get root access on an official RC29 or lower phone, while it’s at the registration screen, or the “no sim card” screen, enable adb (see first tip), and then type the following command on the phone keyboard:
<enter>telnetd<enter>

Now, copy a busybox binary to /data/local/busybox with adb push, and then connect to your phone with adb shell, and give the busybox binary execute permissions (i.e. chmod 755 /data/local/busybox)

busybox has a telnet applet, so you can do:
busybox telnet 127.0.0.1
to get a telnet session with root access.

- If you don’t want to register the phone at all, you can set the app.setupwizard.disable property to 0 to prevent registration. Once you have an adb shell session open, type the following:

setprop app.setupwizard.disable 1

and then reboot. once it loads back up, it should bypass the registration screen all-together.

But beware, the phone seems a bit glitchy if you don’t have it registered. For example, the home button doesn’t seem to work. And you can’t access the market or any of the google apps of course.

(Note: the following was the previous way to skip registration. I’ll keep it here for informational purposes, but its easier to use the app.setupwizard.disable method instead of this)

- If you don’t want to register the phone at all, you can edit /data/system/packages.xml and disable the registration screen. Add the following to the end of the <package> section for com.android.setupwizard, and then reboot:

<disabled-components>
<item name=”com.android.setupwizard.SetupWizardActivity” />
</disabled-components>

so the full <package> would look something like below after the modification:

<package name=”com.android.setupwizard” codePath=”/system/app/SetupWizard.apk” system=”true” ts=”1217592000000″ userId=”10010″>
<sigs count=”1″>
<cert index=”0″ />
</sigs>
<disabled-components>
<item name=”com.android.setupwizard.SetupWizardActivity” />
</disabled-components>
</package>

Original Source: JesusFreke on XDA Developers

This process will take you down to a stock firmware of RC29. If you just leave the phone on, you should receive OTA (over the air) updates automatically within a couple of days, so there are no other files you need to install to update your phone. You should be good to send the phone back in with RC29 if you are doing this for warranty purposes though.

1. Get the original SPL for your phone.

2. Rename it to update.zip and flash it to your phone.
(To flash, copy update.zip to your SD card then boot up while holding the Home key. Press Alt+S after the recovery screen loads to apply the update.zip file)

3. Download the DREAMING.nbh from the thread where you rooted your phone

4. Place DREAMING.nbh on the root of your SD card and start phone in bootloader (CAMERA + POWER)

5. Hit POWER to start the update DO NOT INTERRUPT!! I can not stress this enough!

6. Hit ACTION (push the trackball down) and your phone will reboot.

7. YOU NOW HAVE STOCK FIRMWARE, it will update on it’s own in a little bit.

NOTE: if you have flashed a custom splash screen to splash2 then you will need to erase that before step one with this code. Plug your phone into USB in fastboot mode.

Code:
fasboot erase splash2

After that you will have only one splash screen and when you flash the .nbh you will be fine.

Original source: tubaking182 on XDA Developers

Getting root on your phone involves exploiting a security hole that existed in an early version of Android. The versions with the security holes are known as RC19, RC28, and RC29 (or RC7 or lower for UK phones). As of RC30 (RC8 on UK), Google patched the security hole so that your phone can not be rooted (don’t worry, we can still root it!).
To check your version, go to the Home Screen, click your menu button, choose “Settings”, and then click “About phone”. You will then see the following screen:

<<<Preparing>>>

Backup all of the contents of your SD card. Rooting your phone will wipe your phone and your SD card.

Format your phone’s SD card to FAT32 mode:

1. Hook your phone up to your computer using a USB cable and then wait for the notification to show up in your title bar of your phone.
2. Click the notification, and then click “Mount”.
3. A new removable disk should show up on your computer. Right click it and select Format, and select FAT32 as the file system type.

Either extract all the files in Downgrade.rar to the root of the SD Card, or download each file individually. The Downgrade.rar file includes all of the other files. Currently, only the Downgrade.rar file is available for download so please get it from the link at the bottom.

Ensure your phone is fully charged.

<<<Downgrading>>>

If you have US-RC30/UK-RC8 or higher, you will first need to downgrade your phone to a previous version. (Skip these steps otherwise).

1. Copy Dreaming.nbh to your SD card.
2. Shut down the phone and turn it on holding the power and camera button to enter the bootloader mode. You should see a gray/white screen with instructions to flash your phone with the update on your SD card. If you don’t see that, make sure you followed the instructions properly.
3. As per the on-screen instructions, press the Power button to start downgrade procedure to RC29. DO NOT DO ANYTHING TO INTERRUPT THIS PROCESS.

<<<Installing Test Keys>>>

1. Once you have downgraded to RC29, Reboot the phone.
2. Copy “install” file and recovery_testkeys.img to the root of your SD card.
3. Hit ENTER twice and type the following at the home screen. It will start searching your contacts, but don’t worry about that. Also, you won’t see any visible sign that the first command worked. Just go ahead and type the second command straight afterwards:

cd sdcard<press ENTER>
sh install<press ENTER>

After a moment your phone should reboot itself.

<<<Enabling Test Keys>>>

1. Switch off the phone and then hold down the HOME key while you switch it on again.
2. Keep the home key held down until you see the recovery screen (with the “!” triangle and the picture of the phone).
3. Press Alt+L on the keyboard and if you see “Using test keys” on the second line of text then the modified recovery image is installed

<<<Upgrading to modified RC30>>>

1. Copy the update.zip file to the root of your SD card.
2. You can now install a modified firmware by hitting Alt-S (which will install the “update.zip” file). This is the RC30 file released by JF.

<<<Install Modified Bootloader – Hard SPL (optional but recommended)>>>

1. To install the modified bootloader rename HardSPL.zip to update.zip (then place it to your SD card, deleting the older “update.zip” file).
2. Switch the phone off and then hold down the HOME key while you switch it on again.
3. Keep the HOME key held down until you see the until the new recovery menu, hit Alt-S to apply the new bootloader.

You can only see the skating androids when you power up holding the Power and Camera buttons, it replaces the multicolor recovery bootloader. The boot loader allows you to use fastboot in recovery mode. Once you’re done with the files on the SD card they can be discarded.

<<<Upgrading to Modified RC33>>>

Copy JFv1.42_RC33_MOD.zip to SD card and rename to update.zip. Switch the phone off and then hold down the home key while you switch it on again. Keep the home key held down until you see the until the new recovery menu, hit Alt-S to apply the new bootloader.

<<<Upgrading to a different ROM>>>

Download any ROM and name it “update.zip” and place it onto your SD card. Turn off the phone. Turn it back on while holding the HOME key until you see the recovery boot screen. Press “Alt + S” to apply the update file to flash to a new ROM. Please make sure you have the proper prerequisites for whatever ROM you install before flashing it.

Downgrade.rar – Megaupload (includes everything, or download them individually below)

Dreaming.nbh – 4shared
install – 4shared
recovery_testkeys.img – 4shared
update.zip – 4shared (Modified RC30)
HardSPL.zip – 4shared