Unlocked iPhone 3gs w/ f0recast. - t-mobile's sim card say invalid!

[chayimlife]

Unlocked iPhone 3gs w/ f0recast.
Installed t-mobile's sim card that works perfectly well in my Nokia t-mobile phone.
two quick messages come on screen.. one very small one in the upper left corner says invalid SIM!
Another message in the middle of the screen says SIM failure. both messages go away within a split second.
Went to the t-mobile store and they tried too and experienced the same issue.

do I need to download more/other software to jailbreak/unlock before it is totally unlocked?
the phone is now beyond the emergency screen. in fact all the functions and screens are available.
I can try to make a call. yet there is no service to connect to.
I can even get online via wi-fi .
So what the issue is, I don't know.

To download the f0recast I am used my friends mac laptop with Mac OS 10.5 on it.

My OS is so old that the unlock software will not download.
AND the latest version of iTunes allowed by my OS, will not work with the iPhone.

Another Q:
since I hooked the iPhone to my friend's Mac.. some functions(yahoo IM for instance) on the phone ask for his iTunes password..

how can I change that to use my own user name and PW?

which brings up another question:

I have wanted to access my iTunes account with my iTunes name and PW. However, I have forgotten it. And it doesn't seem like there is a way to reset it.
Any help here?

Thanks

[cybereclipse]

f0recast? you cant jailbreak or unlock with f0recast....
is your 3gs old or new bootrom

[chayimlife]

How do I find out Whether it is OLD or NEW boot rom.?

Thanks

[Hien]

That's what forecast was for.

[chayimlife]

Ok.. again my question is HOW to do this..
Ok use f0recast to check for OLD or NEW boot rom...but how.. what steps do I take?.. and then how to 'unlock' . can you give me a few steps to take?
if f0recast is NOT for unlocking. then what do I use to 'unlock' .
this iPhone was a gift . my boss bought herself a new one and kindly gave me her old one.
Yet it was locked , not showing anything but the emergency call capability.
now after I downloaded f0recast while having the phone USB plugged in , it opened the phone to the apps and all other screens. So I assumed it was unlocked.. obviously it is NOT unlocked for phone service with t-mobile.
happy holidays.

[Hien]

sorry i was mis-educated, f0recast is only good for checking your device model or to see if you can jailbreak installed device iOS?

i dont know what for but here is the link
How to Check iPhone 3GS New Bootrom / Old Bootrom (iBoot) Version | Redmond Pie

i think you havent jailbreak your iphone yet.
what is your iphone firmware now?