---
title: 4011: Recipient phone number required. | API Docs
description: This template can be sent only to a customer whose phone number is known.
---

**HTTP status:** `422`. May also be reported as a field-level finding in `error.details[]`.

The customer is known to this account only by a username identifier, not a phone number, and the named template carries a one-time-code button (copy code, one-tap or zero-tap autofill), which can be delivered only to a phone number. Nothing was sent and nothing was journaled; sending the same template to the same customer is refused again.

## Troubleshooting

- Deliver the one-time code another way; every other message type, including templates without a one-time-code button, can still be sent to this customer.
- details\[].param points at the template part.

## Related

- [Customers who use a username](/channel/whatsapp/guides/messaging/sending-messages/#customers-who-use-a-username/index.md)
- [Templates guide](/channel/whatsapp/guides/templates/index.md)