> For the complete documentation index, see [llms.txt](https://docs.plumvoice.com/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.plumvoice.com/documentation/quick-references/sms-standard-keywords.md).

# SMS Standard Keywords

## Introduction

U.S. mobile phone carriers reserve certain one-word keywords as standard consumer commands within SMS messaging campaigns. These SMS keywords can be categorized as follows:

* **Opt-out**: **STOP**, END, CANCEL, QUIT, UNSUBSCRIBE
* **Customer care**: **HELP**, INFO

These keywords **cannot be modified or repurposed**: these keywords and their use are described in industry regulations defined by U.S. mobile phone carriers and the Cellular Telephone Industries Associated (CTIA).

**Per industry regulations, SMS campaigns must support these standard SMS keywords and provide compliant responses.** The following section describes these keywords in greater detail.

## Standard keywords

{% hint style="warning" %}
**REMINDER:** The following SMS keywords are carrier-reserved and industry standard. These keywords cannot be modified or repurposed, and SMS campaigns must include them to comply with industry regulations.
{% endhint %}

### Opt-out

* **Main keyword:** STOP
* **Universal keywords:** STOP, END, CANCEL, QUIT, UNSUBSCRIBE
* **Description:** The SMS campaign should send an opt-out message after consumers text a keyword indicating that they wish to opt-out. This opt-out message should confirm that the consumer has been opted out of the campaign or service.

### Customer care

* **Main keyword:** HELP
* **Universal keywords:** HELP, INFO
* **Description:** The SMS campaign should respond to HELP with a message containing the service provider's name and additional cotact information.

## Further reading

* [**CTIA Short Code Monitoring Handbook**](https://www.wmcglobal.com/hubfs/CTIA%20Short%20Code%20Monitoring%20Handbook%20-%20v1.8.pdf): Version 1.8; current as of writing (1.31.22)


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