Unlock Blackberry Key2

The Blackberry BB100-5 is a key one, unlocked, dual-sim version. 

Unless you have the wrong information, this phone was never locked to AT&T and never sold by at&t.  The portal is correct, it's not an AT&T phone

AT&T sold the BB key one BB100-1

Sorry, it's BBE100-5. It's a Key2 LE. And AT&T sold it to my mom a few years ago at an AT&T store. The network is AT&T. 

ATT did never sold the key 2 just a FYI....

Okay, well mom is getting up there in years. I guess she's wrong about buying it from AT&T. Does that mean it isn't locked to AT&T? 

Thanks.

Either mom has the model number incorrect, or she didn't buy from AT&T.

If she had purchased it from AT&T, it would still work and it wouldn't be getting kicked off the network. 

If she does have the model number correct, it's an unlocked phone. Non carrier version

It IS a Blackberry Key2 BBE100-5. I guess she bought it at Walmart. So it was a BYOD and she's been using it on AT&T prepaid plan. My understanding is that AT&T locks all byod phones. Is that not true?

It has a dual Sim. Anyone know if I can just use sim2 for another carrier?

My understanding is that AT&T locks all byod phones. Is that not true?

That is not true. It would only be locked to ATT if it was an ATT branded phone. Since @GLIMMERMAN76 said ATT never sold that phone, it’s not ATT branded.

It has a dual Sim. Anyone know if I can just use sim2 for another carrier?

if the phone is unlocked, yes.

It is not possible for AT&T, or any other carrier to lock a phone that is sold as an unlocked, non carrier-branded device.

I suspect your information has something to do with iPhone and Apple's US Flex activation policy. An Apple iPhone purchased at Walmart (target, best buy, and other retailers, except Apple directly) will lock to the first carrier it is used on. Whether that is Verizon, AT&T, T-Mobile, Etc that iPhone then becomes to subject to whatever carrier unlocking policy of that particular phone provider.

This is not true for Android phones.  Android phone either are locked out of the box, or they are unlocked and cannot be locked to any carrier.  

Interesting. I like all these answers. So I should be able to just sign up with hello mobile, then, and the phone will work? The IMEI was accepted. 

It's a t-mo network carrier, so sure.