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Telnyx offers toll-free, long code and short code SMS, conversational SMS, plus MMS. Read the guide below to find out what's best for your use case.

Toll-free SMStoll-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 SMSlong-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 SMSshort-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.
  • Currently only available via long code.

Conversational SMSconversational-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.