In Aus with Telstra there is a filter but they also recommend it, so they may enforce a block upon STOP?
"The SMS scam filter will not block unsolicited or unwanted commercial messages or ‘spam’. To unsubscribe to legitimate business spam or marketing SMS, you can reply STOP."
"The SMS scam filter will not block unsolicited or unwanted commercial messages or ‘spam’. To unsubscribe to legitimate business spam or marketing SMS, you can reply STOP."
https://www.telstra.com.au/cyber-security-and-safety/active-...