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Glossary · Numbering

What is ANI (automatic number identification)?

  • Also called: automatic number identification, ani number

Reviewed by Sujan ThapaliyaLast updated

Definition

ANI is the originating telephone number carried in call signalling for billing and routing purposes. It is distinct from the caller ID a handset displays: ANI is what the network uses, and it is considerably harder to alter than the display name and number.
The three STIR/SHAKEN attestation levels, which underpin how ani (automatic number identification) 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, ani (automatic number identification) included.

In practice

How ani (automatic number identification) actually works

Because ANI exists for billing, it is treated as more trustworthy than displayed caller ID, which is why emergency services and some fraud systems use it rather than the display value. It can still be manipulated in some interconnect scenarios, so trustworthy is relative rather than absolute.

In contact centres, ANI is what identifies a caller before they speak — matching them to an account record so the call arrives with context. Routing on ANI is the difference between a caller repeating their account number and being greeted by name.

ANI and DNIS are a pair: ANI is who called, DNIS is which of your numbers they dialled.

Worked example

A contact centre routing on ANI answers with "Hello Mrs Shah, is this about order 4471?" before she speaks. The same call without it starts with her reciting an account number.

ANI (automatic number identification): common questions

What is the difference between ANI and caller ID?
ANI is the originating number carried for billing and routing. Caller ID is the number and name presented for display. They usually match, but caller ID is far easier to alter, which is why systems that need certainty use ANI.
Can ANI be spoofed?
It is much harder than spoofing displayed caller ID, and in most originating scenarios it cannot be set arbitrarily by the caller. It is not absolute proof of identity, but it is stronger evidence than the display value.
How do contact centres use ANI?
To identify the caller before the call is answered — matching to an account, routing to the agent who spoke to them last, and pre-loading the record so the conversation starts where the previous one stopped.

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 ani (automatic number identification) in the product

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