VoIP number

A number issued by an internet telephony service rather than a mobile carrier; often blocked for SMS verification.

VoIP (voice over IP) numbers route calls and texts over the internet. They are inexpensive and instantly available, which makes them popular for business phone systems and equally popular with spammers.

Because abuse teams know the VoIP ranges, services from banks to dating apps commonly refuse them for verification. If a platform rejects your number "type", this range check is usually what fired.