Yes you can. Tmobile an AT&T both run on a GMS frquency.
Mymalathy answer:
You need to unlock from AT&T Network lock,then you can use the T-Mobile Network,You can use the unlock code to unlock it... after unlock it use your phone with any GSM Network Sim card..
Right out of the box, it most likely will not, unless it was unlocked.
However, both AT&T and T-Mobile operate on the same type of network, GSM. So if you put in a SIM card from a T-Mobile phone into an AT&T phone, then it will most likely ask for the Unlock code. You can get this from different places, however T-Mobile is known to give people the code so that you can use it.
Addition: Answer 2
The Unlock code is slightly different than actually having the phone unlocked. To have it unlocked is something regarding the software inside the phone, that can be altered by a computer. The unlock code is just to access Phone restrictions and security features. MOST phones are locked, and cannot be swapped on sim cards. So far the only phone i have successfully made work on both providers is the Apple iPhone, and that was a Jail broken one.
Joseph's Answer:
Unlocked Cell Phones Can Be Found ALL OVER THE internet ALL DAY LONG.
Search Ebay. Update Yourselves...But Do Not Try and Put The Fear Of God Into Me.
An unlocked AT&T phone WILL work with a T-mobile sim card. I have an AT&T Razr that works with either AT&T/Cingular or T-mobile, depending upon which sim card is inserted.
I called AT&T/Cingular customer service to get the unlock code for my phone - in California, cell-phone companies have to give you the unlock code if your account's been in good-standing for at least 90 days.
If you mean putting an at&t sim card in a t-mobile phone, no. Sim cards only work in phones that are the same brand.
If the T-Mobile phone is unlocked meaning the network unlock code has been given to the phone. Contact T-Mobile for the Unlock code after you have an active AT&T account and sim card.
Yes - providing the t-mobile handset has been unlocked.
You can put any SIM card in an unlocked cell phone.
No, I've tried. You have to insert a special code. (3 tries and the phone locks down) You have to get another att phone.
No most phone companies do not allow any SIM card to go into all phones. The only exception I have found is the SIM cards for ATT phones and TMobile phones.
When you buy a tmobile phone it camoes with a sim card. If you already have a tmobile phone and break it you can buy a pre-paid phone and put your old sim card in it
Yes as long as the phone is att and has a sim card slot
Yes, provided your ATT phone is SIM unlocked.
Yes, provided your ATT phone is SIM unlocked.
The sim card will only work in a different phone if the phone is ulocked, in not, no
YES, you can. IF you have an unlocked code for your at&t phone with T-mobile service. If you don't have an unlocked code, go to your local at&t store and they will unlock it for you, And, you won't lose any information with your T-mobile plan when you put your T-mobile Sim card on your at&t phone.
i believe so, if the phone (unlocked) would be operable if, the GSM version aligns with the providers GSM offering. in other words if an AT and T go phone sim card originally worked through a AT and T phone, and operated on the GSM 1900 bandwidth, then the unlocked phone would have to be capable of working on the GSM 1900 bandwidth. The phone and sim card originally come programmed to operate on a predetermined GSM code and these numbers need to match for swapping to work.
yes u can I had my att go phone unlocked and tried to use my sim card from st. talk which I found out uses att service towers in my area however, it didn't work. It stated "sim crash"
no it does not . it fits into a blackberry 8350I from nextel but it doesnt fit into any tmobile or att.