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Telnyx Messaging Types

Telnyx offers toll-free, long code and short code SMS, conversational SMS, plus MMS.

Toll-Free SMS

Toll-Free numbers are commonly used for appointment reminders, account notifications and emergency alerts.

  • Toll-Free SMS is used to send text messages from toll-free numbers (e.g., 800, 888, 877, etc.).

  • Unlike short codes, toll-free numbers can support both phone calls and SMS, so customers can respond to an SMS alert by texting or calling the same number back.

Long code SMS

Long codes can be used for both person-to-person (P2P) or application-to-person (A2P) use cases like chat applications and customer service.

  • Long codes (long virtual numbers, LVNs or long numbers) are 10-digit phone numbers meant for customer service and operational purposes.

  • Long codes shouldn’t be used for mass marketing campaigns.

  • There’s a potential limit of 200 long code texts per number, per day, if content is similar in each message. This is an estimated number, not definitive — it’s used as a guide to avoid flagging of messages by mobile carriers as SPAM.

  • Most customers send from a pool of long codes, allowing them to increase throughput.

  • You can control auto-responses for long code SMS, however these can be configured only if the committed account is contracted.

Short code SMS

Short codes are commonly used for password resets and alerts.

  • Short codes (common short code or CSC) are 5- or 6-digit phone numbers that customers can lease from the Common Short Code Administration.

  • No opt-in is legally required and for that reason, operators have put more anti-SPAM protections in place. Best practice when using short code SMS is to explicitly ask for opt-ins.

  • Common unsubscribe words such as “stop” and “stop all” are supported and won’t allow any further sending to those customers.


  • Multimedia Messaging Service (MMS) is a standard way to send messages that include multimedia content to and from a mobile phone over a cellular network. Users and providers may refer to such a message as a PXT, a picture message, or a multimedia message. MMS also provides the ability to send and receive attachments.

  • Available with long code and short code.

Conversational SMS

Common use cases include customer support and appointment reminders.

  • Bi-directional SMS provides ability to exchange texts to and from users. This can be possible through either P2P or A2P communication.

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