There is no real quick way of unlocking your newly purchased T-Mobile G1, but there is a fairly simple way of setting up the Google Android based G1 to do just about everything else other than making phone calls, unless of course a VoIP app much like the iPhone’s suddenly becomes available.
To do this you will require the use of a friends activated T-Mobile SIM card for a few minutes and data charges may apply…
Firstly insert your friends activated SIM into the G1 – – power on and wait for set-up screen – – go through the set-up and link any Gmail account – – go into settings > Wireless Controls > Wi-Fi Settings > Enable Wi-Fi – – connect to local WiFi network – – optional: Stop the phone from syncing with Gmail account by going to Data Synchronization and un-checking Auto-sync, Gmail, Calendar, and Contacts – – when done simply remove friends SIM and slip in your own…job done.
Source — loveforbiz