Unable to send texts through my iPad

This has been happening for a while. Have checked previous answers but it seems iOS has changed so much.. non of the answers seem to work anymore.

I have an iPad Pro ios17.7

and iPhone 12 ios17.6.1

about a year ago, the iPad stopped sending texts..

but still shows texts sent by the iPhone.

have tried various things over the year..

any ideas please.. ?

willing to start from scratch again with faulting..

[Re-Titled by Moderator]