can i not use a sim card in another country? i have ATT here in the US, but ATT doesn't exist in Australia.

They only need to be from the same carrier if the iPhone is locked to a particular carrier.

If the iPhone is unlocked, you can use a sim from one carrier, and have the secondary eSim activated with a different carrier.

From the support document you came from:

To use two different carriers, your iPhone must be unlocked

Yes, your iPhone needs to be unlocked to be able to use sim cards from different carriers. This has always been the case. With the dual sim option it is still required. AT&T would be happy to unlock a device: https://www.att.com/deviceunlock/#/

The eSim, is a digital or virtual sim card, there is no little card you can stick inside. Its a built in option. You can add a second phone service overseas through the digital sim card. The carrier you choose overseas needs to be able to setup the digital sim on the iPhone.

Instead of giving you an actual card, they configure the service directly on the iPhone.

The eSim can be used for one phone line, while the physical one, is used for another line.

If you are using a physical sim for your AT&T plan. then you keep using it whether or not you have the eSIM activated.

When you activate the digital sim, it works concurrently with the physical one.

megan1964 wrote:

Interesting. So, I can buy completely unlocked via Apple directly. Then I can go to any provider and ask for connection setup for a US number. Then because I'm not locked to them (ATT), I can then easily get another SIM card overseas and pop it in?

Sort of.

The iPhone Xs comes in 2 dual sim varieties.

The iPhone Xs for everywhere in the world except China, Hong Kong and Macau, features 1 physical sim, and 1 digital eSim. So while you can use a physical sim for one carrier, the second line is a digital one that needs to be supported and setup by the secondary carrier you wish to use. There is no actual physical sim to pop in for the second line.

The iPhone Xs versions for China, Hong Kong, and Macau, do feature dual physical sims, since the digital eSim is not allowed there.

Please read the support document you came from, it explains this in detail.

Also note, that the dual sim functionality will not be available at launch. It will require a software update coming later in the year.

megan1964 wrote:

Well, this isn't good. I just called Apple and asked if my scenario would work and they said yes. I'd be able to go to ATT and activate for myself and then just slip in another sim card when I travel. I purchased the phone. Hope it works. If not, I return it.

As I said, you can use 2 different carriers. But the second one is used through a digital Sim, not a physical one on all models except those meant for China, Hong Kong and Macau.

So yes, you can have 2 different lines, from 2 different carriers, but not 2 physical sim cards to pop in.

Unless you att phone is unlocked anyways you can not us another carrier. And if you us carrier supports the esim then have them use that i believe you can just use a normal sim from another carrier at that point i believe

Well you can, if you want, get it under Apple's iPhone upgrade program, which will let you pay in installments, and it will be unlocked.

iPhone Upgrade Program - Apple

That's correct.