The AT&T SIEMENS SX56, shows an SID Lock after I insert a
T-mobile sim card. Should I contact Tmobile for an unlock code because it's T mobles sim card?

Just changed from AT&T (Cingular) To T Mobile, was working great until I changed the sim card.

Would Flashing the BIOS to T MOBILE correct this ?

Any Suggestions?

Thanks in advance for any assistance

RATTLER

It sure would! If you have the rom built for t-mobile, you can plug it in and it will work...OR..you can search for a thing called xda unlocker..it unlocks your phone so that you can use it with anything..

I have mine setup to use it for cingular (at&t) but its unlock so I can just plug in a tmobile one and it works instantly...

Thanks for the Quick Response!

Appreciate it very much

Hi guys,
You can unlock ur cell through www.gsmlocker.com. My friend used this site for unlocking her cell.

__________________
Thanks

Leon

That is absolutely not an accurate answer. Flashing it with a T-mobile ram will not do the trick.