Help setting up sms to use another iphone number

[thejadedmonkey]

Apologies for the title word soup. I'm not sure what keywords to use.

I have an iPhone 17, it has my main number on it.
I have an iPhone 13 that I prefer, with secondary number on it.

If I remove the sim from the 13, I can text people via iMessage, and it will show up as though I was using my main number.

If I put the sim with the 2nd number into it and try to send an sms, it tells me that the number is unavailable and gives me an option to use the primary number, which ends up being the secondary number. There is no way to send an sms using my primary number anymore.

Both iPhones are using messages in the cloud, and signed into the same icloud account.

Any ideas on what I need to do, in order to send sms messages from the iPhone 13, using my primary number?

FWIW, sending iMessages works just fine on both devices, and any sms messages I get are immediately sync'd to it. It's only sending sms that's causing issues.

 

[chabig]

SMS is a telephony feature, tied to a phone number. So you're stuck with whatever number the SIM has.

 

[thejadedmonkey]

But if I remove the sim completely, it works just fine. That's what I don't get.

 

[VineRider]

On your 17, do you have text message forwarding turned on for the 13? If so, that may be why you’re seeing this.

 

[thejadedmonkey]

Yes. I've also tried toggling it on and off. Using my mac, I am able to send sms via my primary number as expected.

 

[mblm85]

The only thing I can think of is that, as you're using the same iCloud account on both, your iCloud account probably has both phone numbers recorded within it. As you're effectively texting yourself, I think it's getting a bit confused.

 

[Bigwaff]

If I remove the sim from the 13, I can text people via iMessage, and it will show up as though I was using my main number.

That is probably because you are logged into same Apple Account on both devices and you have your iPhone 17 number checked under "You can receive messages to and reply from" while the iPhone 13 number is checked under "Start new conversations from". Go to Settiings > Apps > Messages > (iMessage) Send & Receive on both phones and tell use what you see. I'm also betting your iPhone 13 is listed as a device under Text Message Forwarding.

 

[chabig]

But if I remove the sim completely, it works just fine. That's what I don't get.

A device cannot send SMS messages without being connected to a cellular network. No SIM...no cellular network. I think you are seeing iMessages going out and misidentifying them as SMS. They are not. iMessage uses internet protocols to send message, and Apple's Messages app makes them all look the same.

Even Apple's support documents say that a SIM is required to send SMS. "You can send text messages several different ways in the Messages app...Over cellular service with SMS..."

Set up Messages on iPhone

On iPhone, set up Messages and iMessage to exchange text messages and other media.

support.apple.com

Also, "SMS and MMS are carrier-provided services."

What is the difference between iMessage, RCS, and SMS/MMS? - Apple Support

Learn why some of your message bubbles are blue or green.

support.apple.com

 

[thejadedmonkey]

That is probably because you are logged into same Apple Account on both devices and you have your iPhone 17 number checked under "You can receive messages to and reply from" while the iPhone 13 number is checked under "Start new conversations from". Go to Settiings > Apps > Messages > (iMessage) Send & Receive on both phones and tell use what you see. I'm also betting your iPhone 13 is listed as a device under Text Message Forwarding.

Yes. On my 17, I have my iPhone 13, iPad, and Macbook listed, and they're all toggled on. Under the list, it says "Allow these devices to send and receive text messages from this iPhone"

On my 13, it lists the same devices and has "On" next to them. There's no toggle. Under the list, it says "These devices can send and receive text messages when each device has messages in iCloud turned on". They both have Messages in iCloud turned on.

I think you are seeing iMessages going out and misidentifying them as SMS.

They're green bubbles to an Android phone. 🤷‍♂️

 

[chabig]

They're green bubbles to an Android phone. 🤷‍♂️

What does your Android identify as the sender? A phone number, or an email address? iMessage will work without a SIM...but it won't be "SMS" messaging. That's why I'm asking what the Android sees.

How to Use iMessage on iPhone Without Service (Step-by-Step Guide) - Smarttechtune

Learn how to use iMessage on iPhone without service or SIM. A step-by-step guide for texting with Wi-Fi using your Apple ID.

smarttechtune.com

 

[thejadedmonkey]

What does your Android identify as the sender? A phone number, or an email address? iMessage will work without a SIM...but it won't be "SMS" messaging. That's why I'm asking what the Android sees.

When sending the message via the iPhone 13, without a sim card, my sister said it came from my primary number attached to the iPhone 17.

I'm 100% certain it's using Messages in iCloud to do this, just like my iPad and mac do, except on my phone stops working and defaults to the sim phone number as soon as I put the sim card back in.

 

[thejadedmonkey]

On your 17, do you have text message forwarding turned on for the 13? If so, that may be why you’re seeing this.

Are you suggesting I turn text message forwarding off to get it to use the 17 to send texts via the number on the 17?

 

[VineRider]

Are you suggesting I turn text message forwarding off to get it to use the 17 to send texts via the number on the 17?

Re-reading your original post, I don’t think that will solve your problem as it’s working when the sim is removed from the 13. The conflict appears when the sim is in the 13 so wondering if this is possible to work in the current configuration

Only thing I can think of would be to turn off messages in iCloud on the 13 and see if that makes any difference. However if you do that the messages won’t be in synch on both devices so that could be a blocker for you.


EDIT - Doing some copilot searches, doesn’t seem this is possible

 

[arc of the universe]

Apologies for the title word soup. I'm not sure what keywords to use.

I have an iPhone 17, it has my main number on it.
I have an iPhone 13 that I prefer, with secondary number on it.

If I remove the sim from the 13, I can text people via iMessage, and it will show up as though I was using my main number.

If I put the sim with the 2nd number into it and try to send an sms, it tells me that the number is unavailable and gives me an option to use the primary number, which ends up being the secondary number. There is no way to send an sms using my primary number anymore.

Both iPhones are using messages in the cloud, and signed into the same icloud account.

Any ideas on what I need to do, in order to send sms messages from the iPhone 13, using my primary number?

FWIW, sending iMessages works just fine on both devices, and any sms messages I get are immediately sync'd to it. It's only sending sms that's causing issues.

follow the advice of @chabig .

i would be sure to verify the following:
- you are signed into both phones with the same apple account ID
- you should choose to not use your mobile number as an account id on either phone. delete mobile numbers from being able to be used as a log in number.

i would also wouldn't think about one number being your primary number and one number being your secondary number. the only time its good to think that way is if you have both numbers available in one device.
both of your numbers are primary numbers to their respective devices. you have to think like this in order to figure out your problem.

if your goal is to carry or have two different devices where each one can send and receive SMS and iMessage as well as cellular calls specifically and only to the (e)sim in that device then i would remove all trace of the "other" number from the "other" device. don't allow both numbers to be an account ID on either. have each device with either its own number be able to log into iCloud, or, remove the cellular numbers completely from being able to be used to log into iCloud. delete them from the log in numbers panel.
then, in Settings/Cellular setting make sure there is no trace of second or secondary number. make sure there is only that one number on that phone in Cellular. make sure about this.

(remember that if you are using esim, some carriers limit having two lines active at the same time. if you live in the USA the 17 would be an esim. if this is a concern, then search for DSDS / DSDA to understand about this. although from what you wrote, this issue is not a concern, it appears)

 

[thejadedmonkey]

EDIT - Doing some copilot searches, doesn’t seem this is possible

Dunno how much I trust that. I tried chatgpt and it told me that I can't do it, because phones won't show up in "Text Message Forwarding". Once I let it know that they do, and mine was, it told me I was good to go and it would work. 🤦‍♂️

then, in Settings/Cellular setting make sure there is no trace of second or secondary number. make sure there is only that one number on that phone in Cellular. make sure about this.

That's a good idea! On the iPhone 13, if I try to type my primary number in, it doesn't let me save that number. Other places that the number appears in the phone
* My contact card, as a suggested phone number for me
* Settings -> Messages -> Send and Receive. I can send and receive from the secondary number, although it's unchecked for send/receive and start new conversations.

This number isn't anywhere on my Apple account.

I just want to be able to use messages on my iPhone 13 the same way that I use messages on my iPad. It seems like the existence of a sim card is thwarting me.

 

[mk313]

Nothing useful to add to this thread, but I have the same issue (although I've never had it work & just assumed that was a limitation of SMS). Following in case the OP or someone else finds a solution, as (s)he seems to have gotten it to work at least once.

 

[VineRider]

Is there a reason you couldn't use dual sim on the phone you prefer and just have both numbers on the one phone?