Can't send text messages

This is a problem which has arisen over the last two weeks. I'm running an iPhone 15 on IoS 26.3.1(a).

I can receive text messages but I can't send them. Everything else works, imessage, whatsapp etc but I can't send SMS texts. I get a "Message was not delivered" whenever I try.

Has anyone experienced this and worked out a solution?

Maybe this again👇🏻

To fix iMessage after porting your number, update your phone number in Settings > Phone > My Number to ensure it matches the ported number, not a temporary one. Toggle iMessage and FaceTime off and back on, restart your phone, and allow up to 24-48 hours for the network transfer to fully register with Apple servers.
Step-by-Step Troubleshooting Actions:

• Toggle iMessage/FaceTime: Go to Settings > Messages, turn iMessage off. Go to Settings > FaceTime, turn it off. Restart the phone, then turn both back on.
• Reset Network Settings: Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.
• Sign Out/In Apple ID: Under Settings > Messages > Send & Receive, tap your Apple ID and sign out, then sign back in.
• Check Date & Time: Ensure Settings > General > Date & Time is set to "Set Automatically".

• Verify Number: Go to Settings > Phone > My Number . If it shows a temporary number, change it to your ported number.

This works. I did it myself a month ago. It took around 30 hours so don’t expect an immediate fix. Ride it out. I know it’s a pain but it works. All the best

GaryMc
Thanks for the reply but sadly not the answer. My iMessages work fine for sending and receiving it's only pure SMS text messages where I have a problem and then only sending, I receive them fine.
But you have given me a thought which is that I've not tried the call centre solution, switch it off and on again.

Bingo! - Should have tried that first.

Happy to see that you've managed to get this sorted Perforex! Thanks for helping out GaryMc