---
page_type: error
code: 21212
message: "21212: Invalid 'From' Number"
level: ERROR
---

## Description

You attempted to initiate an outbound phone call or message, but the `From` parameter you supplied was not a valid phone number, Alphanumeric Sender ID or approved WhatsApp Sender.

Twilio accepts phone numbers in [E.164 format](/docs/glossary/what-e164) (i.e. "+1 format"), 10-digit US and Canadian numbers with any combination of non-digit separators, or Alphanumeric Sender IDs (SMS only) with up to 11 alphanumeric characters \[a-zA-Z0-9]. Refer to [this page](https://support.twilio.com/hc/en-us/articles/223133867-Using-Alphanumeric-Sender-ID-with-Messaging-Services) for acceptable characters.

The number must not be on a do-not-originate (DNO) list, and Alphanumeric Sender IDs may not be generic.

### Possible Causes

- You have supplied a phone number that was not in [E.164 format](/docs/glossary/what-e164).
- Your `From` phone number is on a do-not-originate (DNO) list.
- Your [Alphanumeric Sender ID](/docs/glossary/what-alphanumeric-sender-id) is blocked or too generic.
- You are trying to use an Alphanumeric Sender ID on Trial Account. Trial accounts [cannot send from Alphanumeric Sender IDs](/docs/messaging/guides/how-to-use-your-free-trial-account#sending-sms-and-mms-messages).
- Your WhatsApp Sender is not approved.
- You attempted to send a message with a `From` number that has an invalid prefix, using a Messaging Service.

### Possible Solutions

- Ensure your number is formatted in [E.164 format](/docs/glossary/what-e164).
- Ensure that your `From` number is assigned and not on a do-not-originate (DNO) list.
- Ensure you are not using an [alphanumeric sender ID](/docs/glossary/what-alphanumeric-sender-id) that is too generic (for example, "SMS" or "INFO").
- If you are getting this error when using a non-generic alphanumeric sender ID, please [submit a support ticket](https://www.twilio.com/console/support/tickets/create) for further assistance.
- If you are using an Alphanumeric Sender ID on a Trial Account, upgrade your account.
- If you are using a WhatsApp Sender, check that your [sender is approved](https://console.twilio.com/us1/develop/sms/senders/whatsapp-senders) and that you have followed the [onboarding instructions](/docs/whatsapp/tutorial/requesting-access-to-whatsapp).
- If you are sending messages using a Messaging Service, and you wish to utilize an RCS Agent in your Sender Pool that falls back to SMS, [send the message from a MessagingServiceSid](/docs/messaging/services#send-a-message-with-a-messaging-service-1).