Glossary

What is number type intelligence?

Number type intelligence identifies what kind of line a phone number actually is: mobile, landline, fixed VoIP, non-fixed VoIP, toll-free or voicemail. It matters because these types carry very different risk profiles, and a fraud or KYC check that treats every number the same misses one of the cheapest signals available.

The six number types and what they mean

• mobile: a standard cellular subscription tied to a SIM and a carrier.
• landline: a fixed physical line, typically tied to a residential or business address.
• fixedVoip: internet telephony tied to a fixed physical address, such as a business VoIP line, provisioned in a way similar to a landline.
• nonFixedVoip: internet telephony not tied to a fixed address. Cheap and fast to provision, which is why it is the type most associated with disposable-number abuse.
• tollFree: free-to-call business numbers, not personal lines.
• voicemail: numbers that route to a voicemail service rather than a live line.

Why fraud and KYC teams care

A number type alone does not prove fraud, but it is one of the fastest ways to spot a submission that does not look like a genuine customer. Non-fixed VoIP numbers correlate with multi-accounting and disposable-number abuse because they cost little and can be created in bulk; see number type detection for fraud and blocking disposable and virtual numbers at sign-up.

Mobile and landline behave differently for authentication purposes: a landline generally cannot receive SMS, so a landline number enrolled for SMS-based two-factor authentication is a configuration that a genuine customer is unlikely to produce by accident. A toll-free or voicemail-only number submitted at sign-up is rarely what a real individual customer provides, since these types exist for business and call-forwarding purposes. See line-type detection at onboarding for suggested risk logic per type.

How Telebase returns it

The numberType field is returned on every lookup, alongside carrier, country and active status, in a single API call.

{
  "phoneNumber": "+447700900000",
  "active": true,
  "carrier": "EE",
  "country": "GB",
  "numberType": "mobile",
  "simSwap": "UNKNOWN",
  "simSwapAt": null
}

See the full lookup response field reference for how every field behaves, including nullability.