Insights & Resources

SMS Numbers and Traffic Types Explained

The types of numbers you use to send text messages can have a big impact on message deliverability. So it’s more important than ever to understand which option is best for your use case.

Tarek Wiley
SMS Numbers and Traffic Types Explained
SMS has become ubiquitous in our daily communications, and so it's not surprising that businesses have adopted SMS to engage with their customers. With higher engagement and open rates than email, it makes sense to reach out to customers using their preferred channel.
If you’re thinking about adding SMS to your core business functions, it's important to know what kinds of numbers and traffic types exist, and how they differ. The types of numbers you use to send text messages can have a big impact on message deliverability, and business SMS is governed by strict regulations — with significant penalties for getting it wrong. So it’s more important than ever to understand which option is best for your use case.

Which number type should I choose?

Long codes (long virtual numbers, LVNs or long numbers) are 10-digit phone numbers with all the features phone numbers include like voice, fax and international capabilities. Long codes can be used for person-to-person (P2P).
P2P Use Cases - Chat applications, customer service, operational purposes.
10DLC - Long codes used to support A2P traffic in the past. However, in the past year or so, carriers like AT&T and Verizon have launched an initiative which states that A2P traffic must be sent under 10DLC, or 10 digit long code.
A2P Use Cases - Marketing campaigns, notifications, alerts, and higher volume usage.
Short codes (common short code or CSC) are 5- or 6-digit phone numbers that customers can lease from the Common Short Code Administration. Best practice when using short code SMS is to explicitly ask for opt-ins. Example use cases include password resets and alerts.
Toll-free SMS is used to send text messages from toll-free numbers. 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. Example use cases include appointment reminders, account notifications and critical alerts.
Alphanumeric Sender IDs mean you can send messages using a custom ID constructed from a combination of alpha (a-z, A-Z) and numeric (0-9) characters as well as spaces. This makes the sender identifiable to the receiver, as companies can set their brand name as the ID (e.g., TELNYX). It's commonly used for sending one-way text messages, as the person receiving the message will be unable to reply with an Alphanumeric Sender ID.
Hosted Numbers - Hosted numbers are phone numbers that we’ve enabled SMS services on. These numbers could have existing voice services from another provider, or could be for landlines that traditionally have never had SMS capabilities. The voice services of a number are unaffected when you host a number. For more information on hosted SMS on the Telnyx platform, you can check out this how to guide.

Which traffic type is best for my use case?

Telnyx will allow you to select the traffic type that best suits your usage. This will be either A2P or P2P:
A2P messages are sent from an application to a person on the other end. A2P messaging is usually used to deliver high-volume automated alerts, notifications or reminders.
P2P messages are commonly sent from one person to another. Customer support is a good use case, where agents are responding to customer queries.
This table from the CTIA’s Messaging Principles and Best Practices explains that any use case which fails to follow any of the guidelines in the left hand column is considered A2P traffic, and should be sent via 10DLR:
Not sure which type applies to you? CTIA’s Messaging Principles and Best Practices offer a set of recommendations to help guide your decision. Whichever number and traffic type you choose, make sure you’re compliant with SMS regulations -- you can stay informed and on top of your game with our SMS regulations eBook.

To view and change your traffic type:

  1. Sign in to the Telnyx Mission Control Portal.
  2. Click on Numbers in the navigation menu on the left-hand side of the portal.
  3. Click the Routing button [⇄] next to the number you want to check.
  4. Under Messaging Properties, you’ll see your Traffic Type for that number.
  5. To change your traffic type, select either the A2P or P2P radio button and then click Save Changes.
Note: The ability to choose traffic type only applies to numbers eligible for both A2P and P2P traffic.

You can purchase numbers from Telnyx and start sending texts in a matter of minutes. Follow our easy setup guide to get started.
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