United States SMS messaging regulations and restrictions

All SMS messaging in The United States of America is governed by the CTIA – The Wireless Association. Strict rules are in place to regulate USA messaging, and it’s important to work closely with your sales advisor to ensure your program is compliant with the latest regulations at all times.

Note that Federal Communications Commission (FCC) bans SMS messages sent to a mobile phone using an auto-dialer unless prior consent has been received by the user or the message is sent for emergency reasons. The ban applies to all numbers, including those not specified on the Do Not Call list.

Short codes are ideal for marketing messages, any form of bulk messaging, or messages containing URLs. The regulations for US short codes will be provided to you once your application is approved. You can also view the CTIA Short Code Monitoring Handbook. Long numbers are typically used for sending person-to-person communication like appointment reminders, alerts, and announcements. That means you may use it to send messages to customers, employees, and other individuals with an interest in your business. The restrictions below only apply to long numbers.

Our expert advisors are up to date with the latest US messaging regulations and can guide you as you set up and maintain your program. Email expertadvisors@clickatell.com to get started.


Restriction* Description
Sender ID Because all messages must be sent via a long number or short code, a sender cannot have an alphanumeric or other numeric code for sending messages. Your from address must contain your pre-approved US sender number typed in international format.
Opt-in Recipients need to consent to receive marketing communication in writing (i.e. email or other) before you start sending marketing messages to them.
  • Each marketing SMS must contain an opt-out option.
  • Two-way numbers are mandatory to ensure that people can unsubscribe.
Message format
  • Text messages may be a standard length of 160 characters (136 characters in Canada).
  • Unicode is supported and limited to 70 characters per SMS.
  • Concatenation and binary are not supported.
  • The symbol for Euro (€) is not supported.
Content of message
  • The content of all marketing messages must be appropriate for the intended audience, particularly when it comes to marketing to minors.
  • Do not disseminate inflammatory content or content that may cause offense or harm to recipients (deliberately or otherwise).
  • Using keywords or URLs repetitively in the body of long numbers is likely to cause your messages to be blocked by networks.
Message frequency
  • If you send more than one SMS per second, your messages will be rejected by the carriers. Should you require a higher sending frequency, consider purchasing additional numbers.
  • Message volumes for each long number are limited to 5000 per day. Exceeding this limit could result in your number being blocked.
  • On a two-way number, carriers expect to see two-way SMS traffic.

*Table applies to long numbers only



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