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Glossary · Voice technology

What is Carrier voicemail?

  • Also called: network voicemail, operator voicemail

Reviewed by Sujan ThapaliyaLast updated

Definition

Carrier voicemail is the mailbox your mobile network provides, held on the carrier's own systems and reached by dialling a short access number. It is separate from any voicemail your business phone platform provides, and the two can both be active at once.
The three STIR/SHAKEN attestation levels, which underpin how carrier voicemail 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, carrier voicemail included.

In practice

How carrier voicemail actually works

The overlap is the usual source of confusion. If a number is forwarded to a business platform but the carrier mailbox is still enabled, messages can land in either depending on which system answered first — and nobody checks the one they forgot about.

Carrier mailboxes are also the reason a greeting sometimes reverts unexpectedly: the greeting recorded on the platform is not the one the carrier plays.

When moving a number onto a business platform, disable the carrier mailbox deliberately rather than assuming forwarding supersedes it.

Carrier mailboxes are also implemented as conditional forwarding, which is why they interact with forwarding rules in ways that look like bugs. Clearing all forwarding can disable voicemail entirely; setting unconditional forwarding can bypass a mailbox that is still storing old messages nobody can reach.

Worked example

A number forwarded to a business platform while the carrier mailbox is still enabled leaves messages in two places. The one nobody checks is always the one the customer used.

Carrier voicemail: common questions

What does carrier voicemail mean?
The mailbox provided by your mobile network rather than by a phone system or app. It answers when the network decides the call cannot be completed, and it stores messages on the carrier's side.
Can I have two voicemail systems on one number?
Yes, and it happens more often than people realise. A carrier mailbox and a platform mailbox can both be live, with messages landing in whichever answered — which is why one of them always seems to be empty.
How do I turn carrier voicemail off?
Through the carrier, not the handset. It is usually a line setting or a conditional forwarding rule pointing at the mailbox, and clearing forwarding is often what disables it.

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 carrier voicemail in the product

A voicemail drop leaves a pre-recorded message in a contact's mailbox during an outbound call, so the rep moves to the next number instead of speaking the same 20 seconds again. One keystroke, or automatically when answering-machine detection hears a greeting.

Explore voicemail dropGet early access