3GS 4.2.1, 05.15.04...unlock available?

[tfandan19]

Let me know...

[iYeow]

This baseband cannot be unlocked. To get it unlocked and does not work all the time and there is a risk, you can update to ipad 6.15 baseband.
If you have the new bootrom, then it will be a tethered jailbreak. Only oldbootrom gets untethered jailbreak.
Tethered means you have to use a computer to boot up everytime there is a respring or power down.