How to determine if phone was unlocked from factory?

[dslicks2k]

I bought a used Galaxy S5 and the owner claims it is unlocked. I have tried a couple of SIMs from different providers and they both work so I it appears the phone is unlocked.
My question is, how do I tell if the owner paid to unlock the phone through a service or if the phone was bought unlocked from factory?
The reason I am asking is because I don't want the phone to be blacklisted in the future. So far the phone works though.

I am from Canada and the phone's model is SM-G900W8
Thanks

 

[Rukbat]

The phone won't be blacklisted unless the original owner still has his account active and reports it lost or stolen - locked, factory unlocked or paid-for unlocked doesn't even enter into the picture. About the only difference is that some unlock codes you pay for don't work. Evidently his did, so it's the difference between the water in first bucket you pull from the well and the water in the second bucket - there's no way to tell them apart. It's the same unlock code, typed in the same way, in response to the same popup.

 

[dslicks2k]

Thanks for the info!

So technically if the owner still had an account active he could still report it as lost/stolen even though he's made cash for the phone, then I'd be SOL.
If the phone was bought factory unlocked it tells me that there's no active accounts because it was not branded, correct?

Paranoia, argggg

 

[AZgl1500]

If you have a Bill of Sale, or a good solid invoice, you should be okay.

especially if you have been using it for a good bit of time now.

I just cannot imagine the original owner just casually not reporting a lost or stolen phone. That would require him/her to get a replacement phone on his account. That being the case, I feel that you most likely are 'okay'...

If the question should ever come up, the police can back track the sale of that phone from his hands IF he indeed did sell it.

 

[dslicks2k]

No bill of sale or anything..Bought the phone yesterday :S Everything seemed and sounded legit. Nothing scammy about the transaction.

Now I'm thinking if I should just re-sell the phone and get my money back!