Hi Kajolo,
welcomer to the Apple (user-to-user) Community,
Re: "My iPhone suddenly quit sending messages to Samsung"
Wondering if you have updated to the latest iOS version on your iPhone:
About iOS 16 Updates - Apple Support says iOS 16.5 is the latest.
(NB: It is a good practice to back up your iPhone's data before updating)
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Else if you have already updated:
Troubleshooting that may help with some of the possible causes:
Eg: What is the difference between iMessage and SMS/MMS? – Apple SupportÂ
Generally, Messages uses wi-fi to send (blue-bubble) messages to and from Apple users. If wi-fi is not available messages go by cellular data, if it is turned on.
Seems SMS & MMS to Android users use cellular data (green message bubbles):
If your cellular provider's plan includes cellular data:Â
you might want to turn it on if it is turned offÂ
(charges by provider may or may not apply ... you'd have to check).
Apple support have an article online to help:
How to: Use cellular data on your iPhone or iPad - Apple Support
More Info: About Wi-Fi Assist – Apple SupportÂ
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Re: "My phone suddenly quit sending messages to non iPhones".
What to do:
If you can't send or receive messages on your iPhone or iPad
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Re: "The worst part is that everything appears on my phone as if the message went through!"
What to do: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support
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More support if needed:
Apple Messages Support
Messages for iPhone, iPad, Apple Watch and Mac — Official Apple Support
All the best :-)