Subscribers have a clear way to opt out of SMS messages. Critical Impact handles standard English-language reply messages such as STOP, END, CANCEL, UNSUBSCRIBE, and QUIT in accordance with industry standards. These keywords are case-insensitive, so "STOP" "Stop" and "stop" would all be treated as opt-out requests. Also, these keywords trigger automatic replies that can be edited for each of your account's SMS From Short Codes.
If a subscriber doesn't know how to opt-out, instructions are provided. For example, when a subscriber texts HELP or an unknown response, they'll receive an auto-response message ending with a small amount of text to help adhere to industry standards. For example, all Help Responses will end with "Txt STOP to cancel. Msg&data rates may apply." You can also add a helpful phrase like "Reply STOP to cancel" to any of your SMS messages that you send to your subscribers.
Note: SMS message campaigns may be subject to various legal compliance requirements depending on the nature of your text messaging campaign, the location from where you are sending your text messages, and the location of your recipients. While Critical Impact will handle the above-described messages in the way described in this article, you should consult with your legal counsel to ensure that your text messaging campaign conforms to all applicable legal compliance requirements.
Once a subscriber has opted-out, they'll appear in your All Subscribers grid with the checkbox for "SMS Unsubscribe from All" checked. This means that even if they're imported on a future SMS list, they'll be globally unsubscribed in your account and won't receive future SMS messages.
If you need to globally unsubscribe a list of SMS numbers, please read this article.