Thank you bitracer,
I ended up asking ChatGPT 4 and it basically agrees with you!
Here is ChatGPT 4 ’s answer:
Yes, this is a common problem experienced by people who use multiple Apple devices with the same Apple ID.
The issue you’re facing is due to the way Apple handles its iMessage and FaceTime services. When you set up a new device with the same Apple ID, it can automatically register your phone number with iMessage and FaceTime. This is why you’re seeing pop-up messages about adding your phone number to iMessage.
To use both iPhones and still maintain the ability to send and receive SMS and make phone calls, you’ll need to manage your settings.
Here’s a suggested solution:
1. On your primary iPhone, go to Settings -> Messages -> Send & Receive. Here you can manage the addresses at which you can be reached. You’ll see your phone number and Apple ID. Ensure that your phone number is selected under “Start new conversations from”.
2. Do the same thing on your second iPhone, but here, select your Apple ID under “Start new conversations from”.
This way, your primary iPhone will use your phone number for iMessage, and your second iPhone will use your Apple ID.
Also, check the settings for FaceTime, if you use it. They can be found under Settings -> FaceTime -> You can be reached by FaceTime at.
Remember, any text messages or calls sent to your Apple ID will only appear on devices signed into that Apple ID. However, SMS and calls sent to your phone number will be on the device associated with the SIM card bearing that number, and the devices signed into the same Apple ID with “Calls on Other Devices” enabled.
Note that it might take some time for the settings to take effect after the changes. You might need to restart both devices.
Finally, if you find it too complex to manage or face issues, you might want to consider getting a separate Apple ID for the second iPhone. It can provide a more simplified and compartmentalized experience.
