Dual-SIM Messaging: Can't select line

On my new, shiny, iPhone XS (lates iOS,12.1.3), I opted for two lines via eSIM: One is Business, one is Personal.

To phrase this simply: With two lines, how do I choose which line to send messages from?

Now, for more details:

'Personal' is iMessage enabled and default for voice calls.

'Business' is not on iMessage (since you can only choose one line for iMessage with Dual-SIM), and is default for data.

Both lines have data.

When starting a new conversation with my contacts, the "line selector" (as seen in Apple's screenshot, which I've attached) usually does not appear. I cannot understand what decides whether the phone presents the selector or not. For contacts who are registered on iMessage, the phone never presents the selector, and defaults to sending as iMessage via my personal number.

I also can't seem to manually 'force' a reply from one line if someone sends me a message to the other line.

Selecting a line in the person's contact card (for example "Always use: Business") seems to have no effect whatsoever. If their number is set to "Always use: Business", and is registered with iMessage, the phone sends automatically to their iMessage using my Personal line.

iPhone XS

Posted on Jan 25, 2019 12:34 PM

Top-ranking reply

Toot Uncommon

Level 4

1,206 points

Posted on Jan 26, 2019 3:18 PM

When all addresses are iMessage-able, Messages uses iMessage. Otherwise it will use the lowest common denominator i.e. SMS or MMS. I gather that you can only switch the send-from line with SMS or MMS.

I don't know but I believe the image you've parlayed from https://support.apple.com/en-us/HT209044 is merely an example of what you'll see when composing a new iMessage via tapping on the compose new symbol with the line labeled Primary set as the de facto iMessage & FaceTime Line. I see no implication that the Primary label is anything but a cold label, blue for iMessage, or that you can switch the send-from line on the fly with iMessage. The paragraph to the left of the image explains how to change which line is the de facto iMessage & FaceTime Line.

The paragraph below the image explains how you can switch the send-from line with SMS and MMS. It implies that you have to start by composing a new message by tapping on the New button i.e. compose new symbol. I don't know but I gather that then you would see the send-from line label in green and it would be hot-tappable/switchable.

I gather that the per-contact Always use setting will prevail for phone calls and SMS/MMS whenever applicable i.e. an address that isn't iMessage-enabled in the first place or becomes iMessage-disabled later or when Messages falls back to SMS when the iMessage service happens to be contemporaneously unavailable for whatever reason.

Which leaves the question of having two lines and wanting to be able to switch between them on the fly even when all addresses involved are iMessage-acknowledged. That sounds like a sensible capability so maybe it's coming. Dual SIM is new. Good things in life take a long time.

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Dual-SIM Messaging: Can't select line

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