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Glossary · Numbering

What is Number reputation?

Reviewed by Sujan ThapaliyaLast updated

Definition

Number reputation is the standing a phone number holds with carrier analytics engines, built from its calling patterns and complaint history. Good reputation means calls connect and display your name; poor reputation means labelling, silent blocking, and collapsing answer rates.
The three STIR/SHAKEN attestation levels, which underpin how number reputation behaves in practice: A asserts both that the carrier knows the customer and that the customer may use the calling number, B asserts the customer only, and C asserts neither. A shared number pool can reach B at best, which is why number ownership keeps recurring in these definitions.
Attestation is the backdrop to most caller-ID and deliverability terms, number reputation included.

In practice

How number reputation actually works

Reputation is per number and persistent. It survives being released and reassigned, which is why a newly rented number can carry someone else's damage.

It is detected by measurement, not by intuition: the leading indicator is answer rate on one number diverging from the pool average, well before anyone reports a label.

The management pattern is simple: daily dial caps per number, rotation across a pool you own, continuous monitoring, and automatic quarantine of any number whose answer rate drops sharply.

Reputation also travels with the number rather than the business, in both directions. Rent a number somebody burned last quarter and you inherit their score with no way to see it; give up a number you spent a year building and the next tenant gets the benefit. That asymmetry is the strongest practical argument for owning numbers.

Worked example

A number placing 400 calls a day with a 4% answer rate and a 22-second average duration scores badly on every input analytics engines use. The same 400 calls across four numbers with real callbacks does not.

Number reputation: common questions

How does a phone number get a bad reputation?
High daily volume from one number, very short average call duration, a low answer rate, and complaints. Analytics engines score the calling pattern rather than the business, which is why a number can arrive with a reputation you never created.
Can I check a number's reputation before I use it?
Partly. You can call handsets on each major network and see what displays, and reputation monitoring services report labels per number. Neither gives you the full history, which is the strongest argument for owning numbers rather than renting pooled ones.
How long does it take to repair a number's reputation?
Weeks rather than days, and only if the calling pattern changes. Resting a number without fixing volume, duration or list quality returns it to the same score as soon as it goes back into rotation.

Sources

  1. Combating Spoofed Robocalls with Caller ID Authentication — Federal Communications CommissionThe STIR/SHAKEN framework, the attestation levels carriers sign calls with, and the mandate requiring providers to authenticate caller ID.
  2. 47 U.S.C. § 227 — Restrictions on the use of telephone equipment — Cornell Legal Information InstituteThe Telephone Consumer Protection Act itself — the consent requirements, calling-hours limits, and private right of action.
  3. ITU-T Recommendation E.164 — The international public telecommunication numbering plan — International Telecommunication UnionThe international number format, the 15-digit maximum, and how country codes and national numbers compose.

See number reputation in the product

Branded caller ID puts your business name on the recipient's screen instead of a bare number. In North America it works through CNAM, the caller-name record attached to a number, combined with STIR/SHAKEN signing that lets the terminating carrier trust the call is really from you.

Explore branded caller idGet early access