I set up 2 phones, now one phone accepts the others phone call (no 2nd (e)SIM card) ???

My iPhone 11 Pro Max (with it's own dedicated phone number) had an issue with not being able to back up and not being able to do a proper software update because of corrupted somewhere. Long story short, I used a second iPhone (iPhone X with it's own dedicated phone number), factory reset it, then logged in using my Apple ID that I use for my iPhone 11 and set it up like a new phone and then I downloaded the last back up I had from May 2023.

Once that was done and I was comfortable all of my important information was now on the iPhone X, I factory reset my iPhone 11.

Now when I call from my iPhone 11 to my iPhone X, it goes directly to voicemail. If my wife calls the iPhone X, it rings on my iPhone 11. I don't have a second SIM card or a eSIM. To add, I have no problem sending a text to the iPhone X from my iPhone 11 and the iPhone X receiving it.

Also, my iPhone X has it own separate Apple ID's, not the same as my iPhone 11, and the iPhone X has been factory reset and set up like a new phone.

I need to somehow disable this feature and how to do it. Please write out the procedure

Thank you