Transfer Phyical SIM Card Back to Old iPhone?

[NoThx]

I've had a physical SIM card in my iPhone XS for years. A few days ago I moved it over to my new iPhone 13. All was working well. 

Now I'm preparing to go on a trip to a country where Public Mobile doesn't have roaming. So I want to leave my SIM card connected to a phone in Canada. I tried putting the physical SIM card back in my old iPhone XS, but it says error: 

"Your SIM is Not Supported. This phone number can't be transferred because your account is ineligible."

I don't think the new iPhone 13 is using an eSIM because when I remove the physical card it loses service... So why doesn't my physical SIM card work in my iPhone XS anymore?

Thanks 

[NoThx]

Thanks so much. I ended up re-inserting the SIM in my old iPhone for like the 10th time and pop-up appeared that said "Update Carrier Settings". So I tapped that and it worked immediately. I didn't even need to reset the network settings (but that definitely would have been my next step - thanks for the suggestion). Thanks again

[Chalupa_Batman]

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@NoThx wrote:

I've had a physical SIM card in my iPhone XS for years. A few days ago I moved it over to my new iPhone 13. All was working well. 

Now I'm preparing to go on a trip to a country where Public Mobile doesn't have roaming. So I want to leave my SIM card connected to a phone in Canada. I tried putting the physical SIM card back in my old iPhone XS, but it says error: 

"Your SIM is Not Supported. This phone number can't be transferred because your account is ineligible."

I don't think the new iPhone 13 is using an eSIM because when I remove the physical card it loses service... So why doesn't my physical SIM card work in my iPhone XS anymore?

Thanks 

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It should still work. Try doing a network reset on your phone and reboot. That will force the phone to reset itself to the PM network.