can i put my t mobile sim card in my at&t phont?

[MissezPlayfullXD]

well i changed plan from a at&t to a tmobile, but problemm is that i dont want to change phones i berly bout it and i was wondering if i could use my t mobile service in my at&t phone with out getting it locked

 

[jocoolguy]

Without Unlocking you cannot use T-Mobile sim in AT&T Phone...You need to Unlock it...The term is not locking..It's Unlocking.To Unlock a locked Phone get the Unlock code from the site Mobile-unlocker.com and Unlock it easily...Get the Free Unlocking instructions at MobileUnlockGuide.com
unlock it step by step.