iPhone Locked AT&T iPhone 4 takes a T-mobile sim

[Sonic999]

The phone is locked to AT&T, but I tried a t-mobile sim and it took it, shows full bars for a local carrier (Movistar), but won't take any local sims. Under Settings, "more information" it says operator "t-mobile 15.1", Network "Movistar". I even received two text messages, welcoming me to my country, and warning me about data charges. Itunes recognizes the phone, lets me backup, etc.
Can anyone explain how this is possible?

 

[Coleman2010]

The phone is locked to AT&T, but I tried a t-mobile sim and it took it, shows full bars for a local carrier (Movistar), but won't take any local sims. Under Settings, "more information" it says operator "t-mobile 15.1", Network "Movistar". I even received two text messages, welcoming me to my country, and warning me about data charges. Itunes recognizes the phone, lets me backup, etc.
Can anyone explain how this is possible?

It's hard to answer your question when your question is confusing. What do you mean by "took it." And what do you mean by "local SIM?" Movistar isn't a U.S. carrier. ???

 

[JOSE891]

It's hard to answer your question when your question is confusing. What do you mean by "took it." And what do you mean by "local SIM?" Movistar isn't a U.S. carrier. ???

I think he means is he is roaming in another country with a T-Mobile sim card and it connects to whatever network there.

 

[Carlanga]

There is a probability the phone was unlocked by AT&T seeing as it's old.

 

[Sonic999]

Sorry guys, I was away for a few days.
Yes, I'm in another country, Argentina. I have that t-mobile sim because I purchased it in the States while on vacation.
What I meant by "took it" with my broken english (sorry) is that the sim worked with my iPhone... eventhough it is still locked by AT&T. At least that's what I get when I requested that info:
IMEI Number 012543000637xxx
Serial Number 800387FTxxx
Model iPhone 4 Black 32GB
Activated Yes
Telephone Technical Support Expired
Repairs & Service Coverage Expired
Contract Expired
Country Purchased United States
Next Tether AT&T United States
Lock Status Locked

I tried calling AT&T an having it unlocked for free, but it was a no go. Although it's off contract, over 2yrs old, they were asking for information about the previous owner. Proof of purchase, etc.
So I will have to have it unlocked the hard ($$$) way.

 

[Coleman2010]

Sorry guys, I was away for a few days.
Yes, I'm in another country, Argentina. I have that t-mobile sim because I purchased it in the States while on vacation.
What I meant by "took it" with my broken english (sorry) is that the sim worked with my iPhone... eventhough it is still locked by AT&T. At least that's what I get when I requested that info:
IMEI Number 012543000637xxx
Serial Number 800387FTxxx
Model iPhone 4 Black 32GB
Activated Yes
Telephone Technical Support Expired
Repairs & Service Coverage Expired
Contract Expired
Country Purchased United States
Next Tether AT&T United States
Lock Status Locked

I tried calling AT&T an having it unlocked for free, but it was a no go. Although it's off contract, over 2yrs old, they were asking for information about the previous owner. Proof of purchase, etc.
So I will have to have it unlocked the hard ($$$) way.

If you purchased an iPhone locked to AT&T the T-Mobile SIM card should not have worked. Are you sure it's not locked to T-Mobile?

When you try another SIM it does not work? Only the T-Mobile SIM works?

 

[apollo1444]

the fact that you can't use a local sim makes this thread irrelevant the phone is still locked to at&t

you might want to look for a cheap att unlock off ebay they're like $5 bucks

 

[Sonic999]

If you purchased an iPhone locked to AT&T the T-Mobile SIM card should not have worked. Are you sure it's not locked to T-Mobile?

When you try another SIM it does not work? Only the T-Mobile SIM works?

An unlocker told me that this phone would work with any gsm network from the US. I still find that hard to believe, but as I said before, the T-Mobile sim works just fine, at least in my country (roaming)... I dunno if it'd work in US soil.

the fact that you can't use a local sim makes this thread irrelevant the phone is still locked to at&t

you might want to look for a cheap att unlock off ebay they're like $5 bucks

Why irrelevant? I just wanna know how come this "locked" AT&T phone can roam in another country with a t-mobile sim.
And you're a bit outdated regarding unlocking prices for AT&T Iphones... they've gone up to over $60 for a slow unlock (5 to 15 days, 15 days more likely) and $130-40 for a fast unlock (1-2 days).