Five-digit numbers (known as short codes) are used by businesses and automated services to send marketing messages, alerts, and notifications via SMS. Unlike standard 10-digit voice numbers, short codes cannot be blocked at the phone system level — they operate through a separate SMS aggregator network that bypasses traditional call-blocking controls.

How to Stop Unwanted Short Code Messages

If you're receiving unwanted texts from a specific 5-digit number, reply to the message with one of the following keywords:

• STOP — This is the most widely recognized opt-out command and your best option.
• END
• QUIT
• CANCEL
• UNSUBSCRIBE

Legitimate short code campaigns in the U.S. are required by carrier regulations and the CTIA Short Code Monitoring Program to honor these opt-out commands and stop sending messages to your number.

How to Identify the Sender

If you want to find out who is sending the messages before opting out, reply with the keyword HELP. The sender is required to respond with their identity and contact information.

What If the Messages Don't Stop?

If you've replied STOP and continue to receive messages:

1. Report the short code to your carrier. Forward the unwanted message to 7726 (which spells "SPAM") — this is a free reporting service supported by all major U.S. carriers.
2. File a complaint with the FCC. You can submit a complaint at fcc.gov/consumers/guides/stop-unwanted-robocalls-and-texts.
3. Contact us. If you believe the messages are interfering with your service, open a support ticket and we'll help investigate further.

Why Can't These Be Blocked Like Regular Numbers?

Short codes are routed through SMS aggregators and carrier-level messaging gateways — not through the traditional voice telephone network. Because of this, they fall outside the scope of number-blocking features available on your hosted PBX or phone system. The opt-out keywords above are the industry-standard method for managing short code messages.