Questions about how iMessage Works Overseas
February 24, 2017 10:21 AM   Subscribe

I have several questions about how iMessage works overseas when you're using a foreign SIM card in your cell phone. Specifics below the fold...

I have an iPhone with a SIM card from a USA telecom (Ting) and a Macbook Air with iMessage connected to said cell phone (as well as my email address).

Recently, I was on my laptop trying to reset a password from a site that sends an SMS to confirm, but my iPhone was dead, completely out of power.

Somehow this situation had never happened to me before, so I mistakenly thought I'd still get the text message through iMessage. I didn't, until the phone started to charge a little. My fundamental misunderstanding of how iMessage works makes me have a lot of questions:

1) I guess I thought Apple's servers were magically dispensing messages out to available iMessage devices, but it seems the iPhone is receiving the SMS message and bouncing it back to Apple to distribute?

So now I'm wondering how this will affect a future overseas trip. I plan on putting a SIM card from a Japan telecom in my (unlocked) iPhone for maps, etc. And connecting my laptop to wifi, or possible using the iPhone as a data hotspot.

2) So that means SMS messages sent to my USA SIM will disappear into the ether? I won't receive them on my laptop in iMessage, as I originally assumed I would?

3) It seems Japan makes it very difficult to get a Japan SIM with a cell phone number (I think you need to be a semi-permanent resident, provide documentation) and prefers to sell you data-only SIMs instead. Does this mean I can't add the Japan SIM to my iMessage account to send and receive messages?

4) If I, for example, reply to a current iMessage thread (aka previous messages with a USA friend) from wifi or the data-only SIM, does it get sent at all?

5) If you're a frequent traveler, how do you usually handle these issues? My misunderstanding of iMessage made me think this wouldn't be an issue, but now I'm considering getting a USA cell plan that offers better International roaming (T-Mobile or Google Fi).

Thanks for any help you can provide. This has been one of those explodingmind.gif moments where I dumbly assumed things worked differently.
posted by bluecore to Computers & Internet (6 answers total) 2 users marked this as a favorite
I've never seen a password reset or two-factor authentication text come through as an iMessage--they come in as SMS. So, if you have the SMS handoff setting turned on on your Macbook, you'll receive it in Messages there, but only if your phone is turned on and has cell service--your Macbook doesn't have a cell receiver inside of it. iMessage uses data (the internet) which is why you can receive iMessages on your Macbook even if your phone is turned off.

So yes, if you put a Japanese SIM in your iPhone and people send you SMS, you will not receive them. However! Theoretically, if in your iMessage settings on your phone, you have both a phone number and an email address associated with iMessage, you should still receive them, because while that SIM obviously won't have that phone number, your email address doesn't change.
posted by Automocar at 10:29 AM on February 24, 2017 [1 favorite]

Since the message is sent to your US number, it gets delivered directly to your phone using SMS unless it is sent using iMessage. Thus, if you want to receive SMSes overseas you either need to use a different number (either the local number or Google Voice) or use a service that allows international roaming.

If you had an old iPhone that you could leave on back in the US, you would be able to get those SMSes over iMessage on your laptop.
posted by wierdo at 10:32 AM on February 24, 2017

SMS functions outside of the iMessage system. SMS just displays inside the iMessage app for convenience.

Your AppleID is the base ID of your iMessage. A phone number is just associated to that AppleID on a device. See this page for adding or removing an associated phone number.

1. Yes.
2. Correct.
3. If your phone has a data connection, iMessage can/will use your AppleID for iMessage. This is how iPads use iMessage as they have no phone number.
posted by LoveHam at 10:35 AM on February 24, 2017 [1 favorite]

The sending party needs to be using iMessage for it to work, so basically non-Apple hardware (and consequently, automated services) is a no-go. The "seamless" iMessage on iOS devices just checks the phone number you're texting against Apple's database and sends via iMessage if so. (This is how the infamous "can't receive texts from iMessage users after switching away from an iPhone" problem happens.)

When you receive SMS messages in the Messages app on your Mac, that's just the Continuity feature working. The SMS was really received by your iPhone, it doesn't go through iMessage at all. Messages app notes this with "SMS with whoever" or "iMessage with whoever" at the top of the conversation thread.

I *believe* existing iMessage conversations should work no problem, as long as you have net access. At any rate, people should still be able to contact you via iMessage, using your phone number or email address.

If you want to be able to receive SMS messages with just internet access, I suggest Google Voice or a similar service (not sure if GV is still accepting new accounts).
posted by neckro23 at 10:52 AM on February 24, 2017

1) Yes
2) Yes
3) If you have data, you can send/receive iMessages, but you won't be able to receive SMSs.
4) Yes. Your US phone number will be used to identify you, but you can still send/receive from iMessage. You can change whether or not you use your phone number or your Apple ID to send iMessages - - I recommend changing it to your Apple ID.
- US Google Voice account to receive US SMSes.
- Send/receive iMessages done via my Apple ID account, not via a phone number.
posted by suedehead at 11:38 AM on February 24, 2017

If you put a different SIM into your phone, it will deregister your original number from your iMessage account and set the new (local) number as the number it uses for iMessage. (If your number is 212-555-1212 and you pop in a Foreign SIM, iMessage automatically removes the 212-555-1212 number and you will no longer receive iMessages sent to it, on any device. At least that's what happened to us when we put Czech SIMs in our phones on a trip.) Then at the end of your trip when you put your original SIM back in, your phone will reverse that. Even your existing iMessage threads may get messed up because of this, which is why you may want to set your devices to send new messages "from" your email address instead of your phone number. When the 212-555-1212 SIM isn't in your phone, you will receive neither SMS nor iMessage on that number. You can continue to send/receive iMessage on your devices using an email address, as long as you have any sort of internet service, be it wifi, roaming, or cellular data using a local SIM.
posted by fedward at 12:49 PM on February 24, 2017

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