# Why pre-verification fails, and when to try again

Your number's status reads **Failed** and the reason is `verification_code_not_received`. WhatsApp was asked to send a verification code to the number you are connecting, and the code never arrived.

Almost always the number is fine. What failed is the delivery of one message.

## What pre-verification is

Before a number can send on WhatsApp, WhatsApp has to confirm you control it. It sends a short code to the number, either as a text or as an automated call, and Bird reads that code back to WhatsApp on your behalf. You do not have to do anything while this runs: Bird waits about ten minutes for the code, then gives up and marks the number failed.

## Why the code does not arrive

Three things account for nearly every case.

**WhatsApp routes the message somewhere the number cannot receive it.** WhatsApp picks the route it sends verification over, and it sometimes picks one that never reaches your number. Nothing about your number causes this and nothing you change on your side prevents it.

**WhatsApp changes the number it sends from.** In Bird's experience these sending numbers rotate every few hours. An attempt later in the day often goes out over a route that works, when an attempt five minutes from now goes out over the same broken one.

**WhatsApp limits how often it will verify the same number.** Asking repeatedly in a short window gets the requests throttled, which makes the next attempt less likely to succeed rather than more.

## What to do

1. Wait a few hours. This is the whole fix in most cases, and it is why **Try again** on the number's page stays unavailable for two hours after a failed attempt.
2. Open the number from **WhatsApp > Numbers** and select **Try again**. Bird asks WhatsApp for a fresh code and runs the connection through again. You do not need to disconnect the number first.
3. If it fails again, wait longer before the next attempt rather than retrying immediately.

If several attempts spread over a day all fail, contact support. At that point the cause is worth investigating rather than waiting out.

## Prefer a voice-capable number

Bird asks WhatsApp for a voice call whenever the number can take one, and falls back to a text only when it cannot. In Bird's experience a call reaches a number far more reliably than a text does, so a voice-capable number is the single best thing you can choose to avoid this failure.

If you are buying a number to connect to WhatsApp, buy one that supports voice. If you are connecting a number you already own, check whether it can receive calls before you start.

## Next steps

- [Phone number setup](/docs/guides/whatsapp/phone-number-setup): the whole connection flow, and how to recover the other failures
- [Number quality and messaging limit](/docs/knowledge-base/whatsapp/number-quality-and-messaging-limit): what a connected number is allowed to send
- [WhatsApp business verification](/docs/knowledge-base/whatsapp/business-verification): what Meta asks for once the number works

## Related resources

- [Connecting WhatsApp to Bird: from buying a number to a live channel](/learn/whatsapp/connecting-whatsapp-to-bird) (video)
- [Connect WhatsApp](/products/whatsapp) (product)
- [Build your first integration](/learn/paths/integration) (course)

[Get an implementation brief](/learn/workspace?topic=whatsapp-connect)