> For the complete documentation index, see [llms.txt](https://docs.emaillabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.emaillabs.io/en/sms/sms-common-settings/sender-ids.md).

# Sender IDs

The **Sender IDs** section in the EmailLabs panel allows you to manage headers used for sending SMS messages. Below is detailed information about the features and steps for configuring them.

### What is a Sender ID? 

A Sender ID is the header (or sender name) from which SMS messages are sent.

* **Alphanumeric Header:** Enables one-way communication—recipients cannot reply to the received message.
* **2-Way Number:** A dedicated number (9- or 4-digit) that allows both sending and receiving SMS messages directly in the EmailLabs panel.\
  Purchasing a 2-way number is essential for two-way SMS communication.

By default, after creating an account on the platform, the "**SMS TEST**" header is activated, allowing you to test the service.