The Cellular Telecommunications Industry Association (CTIA) regulates all messages sent via SMS service in the United States. The association is essentially a group of wireless carriers and other key players in the mobile space that govern U.S. messaging. You may either send a message through a long code or a short code.

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Your SMS program must be compliant with the latest messaging rules and regulations. In case you do not know, the Federal Communications Commission (FCC) bans sending messages without prior consent from the user. The ban applies to both long and short codes.

Before we discuss messaging rules and regulations, let’s review the basics.

What is an SMS Long Code?

An SMS long code, also called Direct Inward Dialing or a DID, is an SMS-enabled phone number that allows two-way text messaging. In the U.S., an SMS long code is equivalent to a 10-digit number — for instance, 757-544-9510. You can obtain an SMS long code through any SMS provider.

Most of us use SMS long codes when sending messages from our mobile device to others’ mobile devices. This type of message is P2P, i.e., peer-to-peer messaging. However, businesses use long codes for A2P, i.e., application-to-person communication.

Using long codes, you can send and receive messages, place calls, and even send faxes from the same number. Therefore, the consumer does not have to use multiple points of contact. Long codes allow businesses to establish a consistent communication channel with consumers.

Long codes are useful for businesses that require a local number and want to send reminders, alerts, and announcements to users. Long codes are a perfect fit for:

  • Two-way communication
  • Low volume communication
  • Reminders and confirmations
  • Personal alert notifications
  • Group text messaging

Rules Governing SMS Long Codes

Businesses using long codes have specific messaging rules and regulations they are required to follow. They have to adhere to carrier expectations of compliance, and risk incurring fines and carrier audit failures if all FCCA TCPA regulations aren’t followed. Though it may sound daunting, keep in mind that rules for long code messaging are not as stringent as those for SMS short codes.

Terms and Conditions

According to the regulations, businesses must publish SMS-specific Terms and Conditions on a web page when sending messages through long codes. The page must be accessible via a hyperlink from the HELP auto-reply text message.

If you are using a long code SMS program, then your Terms and Conditions webpage must have the following information:

  • Your company’s name
  • “Message and data rates may apply” notification
  • HELP instructions
  • STOP instructions
  • Customer support information
  • Privacy policy
  • Contact Information

Sender ID

Whether you are sending a message via a short code or long code, you cannot use alphanumeric or other numeric codes. Your sender ID or "from address" must include the sender’s number, based in the U.S., and pre-approved. The code must be in an international format.

Sender IDs cannot be blocked, hidden, or otherwise changed to indicate a different sender address.

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Message Format

The standard maximum length for text messages sent via an SMS long code is 160 characters. If you operate your business from Canada, text messages sent through a long code number cannot exceed 136 characters.

Long codes support Unicode with a limit of 70 characters per SMS. Certain special characters and symbols may also not be supported. SMS long codes also generally do not support concatenation and binary. However, Esendex's SMS API offers automatic concatenation for messages that exceed the character limit with guaranteed correct-order delivery.

Opt-In Program

Business must have explicit permission from a recipient to receive marketing messages. This is called an opt-in program and is required for all businesses using SMS long codes. Users may opt-in to your SMS program in many ways, such as:

  • Clicking an opt-in button on a mobile webpage
  • Sending a Mobile Originated (MO) message containing a branded keyword
  • Entering their number online
  • Signing up for your SMS program at a Point-Of-Sale (POS) location
  • Expressing consent over the phone using IVR technology

User consent is also necessary even if a system generates the content of your core messages. According to the carrier regulations for SMS long code, your opt-in message should contain the following mandatory information:

  • Program name
  • HELP instructions
  • STOP instructions
  • Support information

Opt-Out Program

Each marketing message sent via a long code must contain an opt-out program. It is a requirement for recurring-messaging programs to display opt-out /STOP instructions to ensure people can unsubscribe at any time.

If consumers choose to unsubscribe, businesses should remove them from their contact list as soon as possible. Failure to do so can result in negative consumer experiences and fines from the FCC.


A user can opt-out of your SMS program using the keyword STOP. Once the user opts out, you have to send one final confirmation for successful unsubscription. You cannot send further messages to a user added to the opt-out list.

Other keywords that a user may use to opt-out of your program include END, QUIT, UNSUBSCRIBE, CANCEL, and QUIT.


Per carrier regulations, you must send a compliant response to consumers who have texted in the keyword HELP. Responses to the HELP keyword are required, regardless of whether a consumer has subscribed to your SMS program.

Message Content

According to carrier regulations, the content of your messages must be appropriate. Keep the target audience in mind, particularly minors, when generating your message content. The regulations strictly prohibit the dissemination of inflammatory content that may cause offense or harm to the recipient. Whether the message is deliberate or unintentional, you may face an immediate ban.

Similarly, repetition of URLs or keyword stuffing in the message body of long codes may result in message blocks by the networks.

Message Frequency

Under carrier regulations, you cannot send more than one SMS per second through your long code. Violation of the rule leads to the rejection of your messages by the carriers. Incorrect messages may cause a suspension of your service or a fine up to $1,500 per message.

Long codes are suitable for low-volume communication with a message volume of 5,000 messages per long code per day. Exceeding the 5,000 limit could result in number blockage. If you require a higher frequency, you should purchase additional long codes.

Final Word

Compared to short codes, the rules governing long code messaging are less strict. However, they must still be adhered to in order to create the best consumer experience possible.

When used correctly, SMS long codes are a great way to connect with consumers, efficiently communicate, and build brand recognition.

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