# Alphanumeric Sender IDs

> \[!WARNING]
>
> Alphanumeric sender IDs are not available in the United States or Canada. To find out if they are offered in your country, see the [International support for Alphanumeric Sender ID](https://help.twilio.com/articles/223133767) documentation.

An [alphanumeric sender](https://help.twilio.com/articles/223181348-Alphanumeric-Sender-ID-for-Twilio-Programmable-SMS) is a custom identifier that sends SMS messages to [supported countries](https://help.twilio.com/articles/223133767) from a personalized sender name (for example, a business or organization) instead of from an E.164-formatted [phone number](/docs/numbers-and-senders/phone-number-senders).

Alphanumeric senders IDs support *one-way messaging only*; recipients **cannot** reply. They must explicitly opt in to receive messages from an alphanumeric sender ID and must be informed on how to opt out before the first message is sent. Note that recipients can't send replies like "STOP" to opt out so you must provide an alternative opt-out mechanism.

Use alphanumeric sender IDs for outbound SMS notifications, alerts, and other non-interactive messages. When recipients receive your messages, they will see your brand name or business name as the sender ID, helping them identify the source of the message.

## Regulatory compliance registration by country

Some countries require registration of alphanumeric sender IDs before use. See the [country list](https://help.twilio.com/articles/223133767-International-support-for-Alphanumeric-Sender-ID) to check whether registration is required.

To submit a compliance registration, follow the steps on how to [create a registration for alphanumeric sender IDs](/docs/trust-hub/registrations#alphanumeric-sender-id) in Trust Hub.

## Getting started

To set up a new alphanumeric sender:

1. Log in to the Twilio Console.
2. Navigate to **Products & Services > Numbers and Senders**.
3. Select the **Alphanumeric senders** tab and click **Set up a new alphanumeric sender ID**.
4. Follow the on-screen prompts to complete set up.