SMS not working on IOS 18.3.2

Hi everyone

I am having the strangest problem. I am able to receive SMS but i am unable to send.

Clearly this is a problem regarding the message center number, which is wrong. None of the codes like *#5005*7672 will work. Tried all other suggestions like reset network settings, Imessage turn off/turn on ( my number is not activating). Also called my service provider which gave me the "brilliant" idea to use an Android phone in order to save the sms settings on the SIM card ( that didn`t work either), after which they told me to try the same thing using a Samsung phone ( that i didn`t try yet, but is seams stupid). Just to answer ahead, no, i don`t have any carrier updates. Can anyone help?