Hola a todos mis amigos usuarios de G1 mirando en algunos foron encontre esta informacion que espero sea de ayuda para todos ojo esta en ingles
More detailed T-Mobile G1 unlock instructions after the jump.
You’ll need an Android-powered T-Mobile G1 running RC30 with root access - that means you updated your G1 to RC30 using this workaround method to preserve root access.
You must have root access!
Download the unlocked bootloader here.
Rename the unlocked bootloader file to “update.zip”
Move the newly renamed “update.zip” file to a microSD card.
Insert microSD card into G1.
Restart the handset by holding down the “Power” and “Home” buttons simultaneously
When you see the triangle logo (you’ll know it when you see it), hold press “Alt” and “L” simultaneously
Ensure that you see “using test keys” along the top
Press “Alt” and “S” simultaneously
Follow the on-screen instructions
Press “Home” and “Back” buttons simultaneously when you’re done and ready to reboot
The G1 will reboot as it does its thing - let it do so.
You have now hacked/unlocked your T-Mobile G1 to work just like an Android Dev Phone 1 - enjoy all those unsigned Android builds and the freedom to use whatever GSM network tickles your fancy!