How do I toggle between 2 SIMs when using the Phone app?

Thank you for this info. I use the same carrier for both lines. I see this quote from the first link:

• If you make a phone call from another device, such as your Mac, by relaying it through your iPhone with Dual SIM, the call is made using your default voice line.

This doesn't sync with what the literature says about using the Phone app. You're supposed to have the option to switch lines per this information:

1. Go to the Phone app  on your Mac.
2. Click , then do any of the following:

• • Use a different line: On models with Dual Sim, click the line at the top, then choose a line.

Hi MrHoffman,

Setup steps have been done. I've been using both lines for over a year.

This is an iPhone 15 Pro. I'm in the US.

I am trying to do this on a MacBook Air M1, but from what I've seen and read, I'm supposed to be able to select the outgoing line from the keypad, as seen in this image at the upper left:

Sadly, no. This is what I see:

This is strange... It works correctly on my iPad! 😂 The iPad is WiFi only.

Not sure why I can't do the same thing on MacBook Air.

Well, it's working on my MacBook Air now. I may have "fixed" it by re-enabling iPhone Mirroring, then rebooting the MBA. I can now toggle between the 2 SIMs like I can on my iPhone and iPad.