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Improve SMS Deliverability with Fallback to Long Code


  • Resends messages from a long code phone number when a message can’t be delivered by short code.
  • Free to use.
  • Available now in public beta.

Getting text messages delivered in the US and Canada is complicated business. North America has one of the most highly regulated telecommunications environments in the world. Figuring out all of the nuances and dealing with them can be daunting, but never fear, Twilio has your back.

To give you better performance, we’re continually improving the software intelligence of our platform. Today, we are excited to announce Fallback to Long Code, a new feature of Copilot. When a short code message is undelivered, Copilot will automatically resend the message from a long code phone number. The Fallback to Long Code feature is free to use and you only pay the standard cost for sending messages. You can enable it for any messaging service in the Twilio Console.

Short Codes

While a long code is a standard phone number (10-digit numbers in many countries) used to send and receive voice calls and SMS messages, a short code is a special 5 or 6 digit telephone number designed for high volume use cases.

Delivery Rate

Short codes have a higher delivery rate than long codes for “application to person” use cases such as marketing, promotions, alerts, notifications, and two-factor authentication. Long codes are subject to carrier filtering, while short codes are pre-approved by carriers to not be blocked as spam.

Why Short Code Messages Go Undelivered

Although short codes don’t get filtered for spam, the delivery rate isn’t 100%. Two of the biggest factors in short code deliverability are disabled accounts and carrier support. To understand why this impacts deliverability we’ll explore some of the history of short codes in the North America.

Disabled Accounts — Remember Ringtones?

In the early days of mobile texting, short codes were originally conceived to provide “premium” services. Mobile users could purchase ringtones, donate to charities, and vote for TV talent competitions using short codes. The price charged for sending a short code message could be much higher than a typical long code SMS. For example, you’d be charged $5.99 for texting “pac1” to this short code and in return you’d to get a snappy Tupac California Love ringtone.

Due to the additional charges, short codes could be disabled on an account basis. Each individual could choose to disable short code messaging for their phone. Fast forward to today and some users may have short code messaging disabled because they simply forgot about it. They sign up to receive text messages from a service that uses short codes, but they don’t receive these messages even though they want them.

Carrier Support and Common Short Codes

Originally, all carriers had their own short codes. The same number could be used for different purposes depending who you used for mobile phone service. This of course caused great confusion. Thus common short codes were created. Common short codes are numbers that are agreed upon by most carriers to work across all of their networks. For folks that buy mobile services from large carriers like T-Mobile, AT&T, Verizon, or Sprint it means everything tends to work great.

However, some folks purchase discount services from smaller operators. These smaller operators may not be set up to receive traffic from particular short codes. As a result users on their network don’t receive short code messages—even if they want them.

How to Get the Highest SMS Delivery Rate

Copilot has two intelligence features to solve these deliverability challenges: Short Code Reroute—a part of Copilot since it launched, and now Fallback to Long Code. Both work by using long codes in addition to short codes to send your messages.

  • Short Code Reroute automatically sends messages with a long code to carriers that don’t support short code messaging.
  • Fallback to Long Code sends messages with your short code first, and when a message is undelivered, it falls back to a long code. This ensure even accounts with short code messaging disabled still get the message.

Together, Short Code Reroute and Fallback to Long Code allow you the reach the most users with your messages.

Getting Started

Both Short Code Reroute and Fallback to Long Code work by using long code phones numbers. To use these features you’ll want to make sure you add several long codes to your messaging service in addition to your short code(s). The Copilot Short Code Reroute feature is enabled by default.

It’s simple to enable Fallback to Long Code:

1. Visit the Messaging Services section in the Twilio Console.

2. Add long codes to your existing service. (Create a new service if you aren’t already using one.)

  • Click on the messaging service to configure it.
  • Click on “Numbers” in the sidebar.

Visit Messaging Services in the Twilio Console

  • Add your short code(s).
  • Add some US and/or Canada long code numbers.

Add US and CA numbers to your message service

3. Click on “Configure” in the sidebar to visit the configuration page.

4. Click on the check box to enable Fallback to Long Code.

5. Then click save.

Configure Fallback to Long Code

That’s it! Now, you’re set up with the highest level of deliverability available.

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