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Help Text not sending to one single phone number


Jan 1, 2023
Hi guys! Quick rundown of what's going on; after years of not being able to text my grandmother I'm finally seeking help figuring this out.

1. I have a Fold 4, Grandma has an iphone (not sure which one)
2. When I text her I get a failure to send message (in both samsung and google's messaging app)
2a. When she sends me a message she also gets a not delivered message
3. Neither of our numbers are in blocked numbers categories
4. Both of us deleted each others contacts and re-entered the numbers. Calls go through fine.
5. Send SMS is check on, on the iphone. Network reset was done
6. Android messaging apps caches are cleared.
7. Imessage was confirmed to not be registered to my phone number.

Any solutions?
Last edited:
Are you certain you are sending SMS rather than using RCS messaging, which is marketed as "Chat"? Both Google and Samsung apps support this (many others don't), but it does not work with iPhones. I can't say more about it because I know nobody who uses it and so have never enabled it (and use an app that doesn't support it myself).

Have you spoken to your respective service providers to see whether they can work out why messages are not going though?
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Have your Grandma check the Settings menu in her iMessage app to see if support for SMS and MMS is enabled:

The fundamental problem is Apple's iMessage app is by design intended to function using its own, proprietary iMessage protocol. Apple users tend to use only the iMessage app within Apple's inclusive environment so it works exceptionally well with Apple-to-Apple users. Fortunately Apple does include support for SMS/MMS in its app but it might need to be enabled by the user. Currently there are dozens of different text messaging protocols that compete with each other (I.e. WhatsApp protocol is not nor will ever be interchangeable or compatible with the iMessage protocol), and the only two protocols that all text messaging apps/services still support are the very dated and obsolete SMS and MMS standards. (Well, Signal just recently dropped support for SMS/MMS but it's a highly security-focused text message app so a bit of an outlier.) But basically, Apple doesn't bother to support any other third-party text messaging protocols, nor will it allow other text messaging apps/services to include its iMessage protocol. It has a really robust texting service in place, it doesn't need to mess with the noise from all the other competing protocols. With Android, Google is pushing its RCS protocol (a proprietary standard owned and managed by Google but pales in comparison to Apple's iMessage protocol) but given Google's very dismal history on text messaging in general, it's not a matter of if but when Google just kills off RCS too.
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