Are AT&T contract iPhone 6s plus unlocked?

We just got an "on contract" AT&T iPhone 6s plus phone (through our family business account) a few months ago. We want to know if when we're traveling to Asia and Europe, is the phone already unlocked? Can we just use a prepaid sim for the country we visit? How can we find out. My wife's friend told her that "All US phones sold in the last 2 years are always unlocked." Is this true? If it is locked, how can we get it unlocked, if we're still "on-contract"?

Buy la cheap local prepaid phone!

They are locked. AT&T will unlock the phones after you fulfill your contract.

As far as I know those phones are locked. Verizon sells their iPhones unlocked but not AT&T.

If you can settle for a Nexus 6p or 5x Google's Project Fi seems to have pretty good prices for taking calls overseas.
I believe they are locked to AT&T and you would buy an Unlocked to SIM carriers for full price form the Apple Store. Since AT&T likely has roaming everywhere they are likely locked to AT&T

All AT&T phones are sold locked. Once a phone is activated it is locked to the carrier for at least a year.

Any phone in a contract is locked until it is fully paid off.

Google it

Unfortunately, no. Any phone that you purchase on a contract is locked to that carrier until the phone is paid for. It doesn't matter if you terminate the contract or remove the SIM card. The phone is still locked and won't work on any other carrier. The phone will be unlocked once the phone is fully paid for, assuming you didn't pay the full amount for it. Example a brand new iPhone can cost anywhere as low as $600, but when getting one on a new contract, you pay $200 down and the phone payments are included in the plan. The phone is also unlocked once the contract reaches it's expiration date which is after the two years are over. Also, even if you are on a contract, your carrier will not unlock it for use on another carrier until you pay for the remaining amount on the phone and terminate the contract which can cost around $350.00 in the US

If you can settle for a Nexus 6p or 5x Google's Project Fi seems to have pretty good prices for taking calls overseas.
I believe they are locked to AT&T and you would buy an Unlocked to SIM carriers for full price form the Apple Store. Since AT&T likely has roaming everywhere they are likely locked to AT&T

Nope. They want their phones locked so that people won't go and use them to get unlocked phones to use on other networks