What is a phone reputation check?

A phone reputation check assesses how much a phone number can be trusted as a contact point for a real person: whether the number is valid and assigned, which carrier holds it, whether it is a mobile line or a VoIP number, and whether anything is registered to it. The purpose is separating a long-held personal mobile from a disposable number acquired for a single account.

Does the Digital Footprint API return a phone reputation score?

Yes - a 0-100 phone risk score, and it is explainable. The score is the sum of the named signals that fired, such as an internet (VOIP) number or a number anyone can create in an app, and each signal comes back with its points. Accounts can turn default rules off, change their points and add their own rules, so the score carries your thresholds.

What is the strongest signal in a phone check?

Line type. A VoIP or non-fixed-VoIP number is cheap, disposable and available in bulk, while a postpaid mobile line requires identity and payment at the carrier. That single distinction separates most disposable numbers from most real ones and costs nothing to read - a VoIP line is not evidence of fraud, but it is a reason to want a second signal.

How many platforms can be checked with a phone number?

A phone number can be checked on WhatsApp, Telegram, Facebook, Instagram and X (Twitter), each priced separately and billed only when it runs. Most platforms are keyed on an email address or a username, which is why an email reaches further than a number does - so when both are known, send both.

Can a phone number be checked against carrier or spam databases?

Carrier and line type come back from number intelligence, so the carrier question is answered. Spam and scam-report databases are a different source that this API does not query, so no complaint history or spam rating is returned. If a spam list is part of your requirement, treat it as a separate vendor and combine the two rather than expecting one answer here.

Phone reputation check: what a number can and cannot tell you

Updated 2026-09-29

A phone reputation check is meant to answer whether a number belongs to a real, reachable person or to a disposable VoIP line bought for one signup. This guide covers the signals that genuinely answer that - line type, carrier, validity and messaging-app registration - and explains how the phone risk score reads them - as a total of named signals you can see and tune, not a black-box rating.

What actually comes back

A phone lookup returns number intelligence, registration on the platforms that accept a phone number, and a risk score whose every point is traceable to a named signal.

200 OK

{
  "footprint": {
    "results": [
      { "platform": "whatsapp", "registered": true, "identity": "phone", "checkedAt": "2026-09-29T09:12:04.1Z" },
      { "platform": "telegram", "registered": true, "identity": "phone", "checkedAt": "2026-09-29T09:12:04.3Z" }
    ]
  },
  "phone": {
    "valid": true,
    "countryCode": "US",
    "carrier": "Verizon Wireless",
    "lineType": "mobile",
    "isVoip": false,
    "risk": { "score": 0, "signals": [] }
  }
}

Read phone.lineType first. It carries more weight than the other three fields combined, for the reason below.

Line type is the signal that matters

Numbers are not interchangeable. A postpaid mobile line is issued by a carrier that took identity and payment details for it, and it is expensive and slow to acquire in volume. A non-fixed-VoIP number can be provisioned in seconds, in bulk, from a browser, and discarded just as fast. When a fraud team asks whether a number is “good”, this is very nearly the whole question.

What line type does not tell you is whether the person is legitimate. Plenty of real people use VoIP numbers deliberately - remote workers, people who moved country, anyone who prefers not to hand out a personal mobile. It is a reason to want a second signal, not a reason to decline.

Messaging-app registration

A number can be checked on WhatsApp, Telegram, Facebook, Instagram and X (Twitter). A number registered on a messaging app is positive evidence that somebody uses it; a fresh VOIP number registered nowhere is a very different profile. When you also hold an email address, send both in one request - see the email enrichment API - and the WhatsApp number check guide covers choosing platforms.

How the phone risk score works

The score is the sum of the rules that fired, capped at 100, and every fired rule comes back with its id, label and points. Nothing is hidden inside the number: a reviewer who asks why an application scored 25 sees exactly which two signals made it 25.

The rules are yours to tune. Switch a default rule off, change its points, or write your own on the same facts - see fraud risk scoring. A fact that could not be established never fires a rule, and a module with nothing to evaluate scores null, never a reassuring 0.

Frequently asked questions

What is a phone reputation check?: A phone reputation check assesses how much a phone number can be trusted as a contact point for a real person: whether the number is valid and assigned, which carrier holds it, whether it is a mobile line or a VoIP number, and whether anything is registered to it. The purpose is separating a long-held personal mobile from a disposable number acquired for a single account.
Does the Digital Footprint API return a phone reputation score?: Yes - a 0-100 phone risk score, and it is explainable. The score is the sum of the named signals that fired, such as an internet (VOIP) number or a number anyone can create in an app, and each signal comes back with its points. Accounts can turn default rules off, change their points and add their own rules, so the score carries your thresholds.
What is the strongest signal in a phone check?: Line type. A VoIP or non-fixed-VoIP number is cheap, disposable and available in bulk, while a postpaid mobile line requires identity and payment at the carrier. That single distinction separates most disposable numbers from most real ones and costs nothing to read - a VoIP line is not evidence of fraud, but it is a reason to want a second signal.
How many platforms can be checked with a phone number?: A phone number can be checked on WhatsApp, Telegram, Facebook, Instagram and X (Twitter), each priced separately and billed only when it runs. Most platforms are keyed on an email address or a username, which is why an email reaches further than a number does - so when both are known, send both.
Can a phone number be checked against carrier or spam databases?: Carrier and line type come back from number intelligence, so the carrier question is answered. Spam and scam-report databases are a different source that this API does not query, so no complaint history or spam rating is returned. If a spam list is part of your requirement, treat it as a separate vendor and combine the two rather than expecting one answer here.

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