Confused, 3GS on emergency screen need help

[Adenosine]

I must be getting old. I have been reading and reading only to be more confused.

Here is what f0recast tells me I have.

BB: 05.15.04
Bootloader 6.4
FW 4.2.1

I don't have the AT&T sim card for this phone. I would like to use it on my TMO service. I thought by reading I needed to go to the iPad 06.15. I tried with redsn0w (redsn0w_win_0.9.6b6) on my windows machine. I pointed it at the file:

iPhone1,2_4.2.1_8C148_Restore

Followed the instructions and it locked up on waiting to reboot. looked that up did what others have done such as re-enter DFU and it did go by that screen. Afterwards, Redsn0w said finished and nothing changed.

Obviously I'm not getting it.

Thank you for any help.

[Dadastar]

Your FW is for 3G , not 3GS .

3GS' version should name iPhone2,1.....

[Adenosine]

Thank you, knew it must have been a simple problem. Up and running 06.15.00 and on T-mo now. Thank you.

Look forward to the untethered version.