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Short codes (common short code or CSC) are 5- or 6-digit phone numbers used for high-volume, application-to-person (A2P) messaging. They’re commonly used for two-factor authentication, marketing campaigns, alerts, and notifications.

Prerequisites

  • A Telnyx account in verified status
  • A messaging profile configured in Mission Control

Setting up a short code

1

Request a short code

Navigate to Short Code in Mission Control and submit your short code request. You can request a random short code (carrier-assigned) or a vanity code (a memorable number you choose, subject to availability).
2

Complete carrier certification

Once submitted, your short code campaign goes through carrier certification with the major US carriers. This process typically takes 8-12 weeks.
3

Start messaging

After approval, your short code appears under the messaging profile you specified. You can send and receive messages just like you would with long codes.

Automated responses

Telnyx sends automated responses from short codes to pass carrier certification tests and handle opt-out requests.

Trigger keywords

Automated responses are generated when the short code receives:
KeywordPurpose
KEYWORDCampaign-specific keyword response
HELPProvides help information
STOP (and similar)Confirms opt-out

Customizing automated responses

After carrier certification is complete, you can disable automated responses for KEYWORD and HELP to handle them yourself. Contact [email protected] to make this change.
Opt-out (STOP) responses cannot be disabled. Once a user opts out, they are blocked from receiving messages, which prevents you from sending a custom response.