Howto Upgrade your Android G1 to the Latest Radio & SPL

First you need to update your radio to the latest before applying this spl to avoid bricking your device. You also must flash one of the newer roms that support the new radio/spl which are dudes, cyanogens, or any hero rom.

This SPL is optional and optimized for hero and rogers roms, if you flash the spl make sure you have a nandroid backup or rom to reflash because you will need to do so.

The latest Radio version is 2.22.19.26I with a Baseband Version of 62.50S.20.17H_2.22.19.26I

Download the radio to /sdcard/update and download the SPL here to /sdcard/spl-signed.zip


Shutdown your phone and press Home + Power while booting to get to the recovery console, then press ALT-S to flash, once its finished and done rebooting twice, go back into the recovery console.
Press ALT+X for terminal, press Enter, then type:
mount /sdcard
cd /sdcard
mv update.zip latestradio.zip
mv spl-signed.zip update.zip
cd ..
umount /sdcard
recovery #Sends you back to the recovery screen
Press ALT+S to flash the new SPL after your successfully flashed the new Radio!