Why can't receive sms from truemove-h in Singapore (again) even though already enabled WiFi calling?

Cannot receive sms for my truemove-h number (again)

it happened last year and i went back to thailand to enable wifi calling over the counter, and it worked for a while after i came back to singapore, but recently it shows 'no network' (can't connect to any service provider), and cannot receive sms. Please help urgently