What does it mean if the phone number I checked shows up as 'unverified' in the check outcome?

If a phone number shows up as unverified in the check outcome, this means that the phone number is:
Not a registered sender under SSIR (SMS Sender ID Registry) by IMDA.
This registry is meant for organisations intending to use alpha/numeric/alphanumeric Sender IDs in their SMS messages.
Not blocked or marked as scam in the ScamShield database.
This verification only applies to senders who fall in either of the 2 categories above. If a phone number doesn't fall in the above 2 categories, it will show up as unverified in the check outcome.
Please note that SSIR whitelisting is not applicable to your personal phone number as a ScamShield user. If you check your own phone number, you will still get 'unknown sender'. However, if your phone number shows up as 'Suspected to be a scam', this means the phone number has been blocked by ScamShield as it was deemed suspicious based on community reports.