Twitter Blue

Hi

when attempting to verify my Smarty number with Twitter I get the following error message ‘we cannot send a text message to this phone number because it’s operator is not supported.’

This is on an iPhone 14 with latest software, I get the same on pc.

I have raised tickets with Twitter and they say it’s Smarty, Smarty say there’s nothing they can do?

Has anyone experienced this issue and been able to fix?

Thanks