---
title: "Opt-In To Receive SMS"
slug: "opt-in-to-receive-sms"
description: "Learn how Customers provide permission to receive SMS communications."
updated: 2025-09-03T18:28:53Z
published: 2025-09-03T18:28:53Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.gladly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Opt-In To Receive SMS

Customers opt-in to receive SMS messages from your company by sending a text to your [advertised](https://help.gladly.com/docs/sms-consent-and-compliance-guidelines/#include-optin-language-in-your-%E2%80%98contact-us%E2%80%99-web-page) SMS-capable phone number configured in Gladly. When they text for the first time, their phone number is automatically tagged as **Mobile + SMS** in the Customer's[Contact Details](https://help.gladly.com/docs/tag-a-phone-number-as-sms) card.

They should also receive an initial reply confirming that their message was received with information on how to [opt-out](https://help.gladly.com/docs/sms-opt-out-keywords) of SMS messages anytime.

If texting a Customer who has [opted out](https://help.gladly.com/docs/sms-opt-out-keywords), the error "The destination number has disabled receiving messages from this number and must text 'START' to this number to enable" appears.

The Customer must reply with **Start**, **Unstop**, or **Yes** to re-subscribe/opt-in again to the number they previously unsubscribed from, which unblocks their number from receiving SMSes from Gladly. Upon opting in, the response sent to Customers (e.g., you replied "unstop" and will begin receiving messages) is carrier-generated and cannot be modified or customized.

Opting in [automatically retags the Customer number as SMS](https://help.gladly.com/docs/tag-a-phone-number-as-sms), allowing Gladly to send messages again. For additional information about SMS opt-out keyword requirements, please see [support for opt-out keywords (SMS STOP filtering)](https://support.twilio.com/hc/en-us/articles/223134027-Twilio-support-for-opt-out-keywords-SMS-STOP-filtering-).