Unlike standard long code phone numbers, toll-free numbers are designated for business use in the United States. Although carrier filtering is still possible for messages sent from toll-free phone numbers, you can greatly reduce the likelihood of filtering by complying with all regulations, and following best practices. This guide explains what SMS use cases are approved for toll-free phone numbers, and our recommendations for ensuring high deliverability.
Approved toll-free SMS use cases
Only transactional SMS use cases have been approved for sending over toll-free phone numbers. These include the following:
- One-time password (OTP) or verification codes
- Account-related alerts or notifications
- Customer care messaging that includes some automated messaging (including satisfaction surveys)
Bulk marketing or promotional SMS use cases are not acceptable over toll-free phone numbers, and will be subject to filtering.
Toll-Free SMS best practices
Toll-free SMS filtering is primarily geared toward preventing unwanted messaging, fraud, or abuse, rather than blocking application-to-peer (A2P) type traffic. If you are sending A2P messages to the US that align with the CTIA's best practices, you should generally see reduced filtering when using a toll-free phone number (versus standard filtering with a long code phone number).
Additionally, Twilio recommends toll-free SMS users adhere to the following standards:
- Obtain clear opt-in from your recipients before sending them messages (the opt-in does not need to be via SMS).
- Provide easy ways for your users to opt-out of messages.
- Maintain a very low opt-out (STOP reply) rate from your recipients.
- Do not send lots of identical content, particularly anything which is (or may resemble) bulk SMS marketing.
- Do not "load balance" by sending the same or similar message contents using multiple toll-free numbers. This is specifically targeted for filtering on toll-free SMS.
My toll-free SMS to the United States are being filtered, but my use case complies with all best practices
If you suspect you may be experiencing inappropriate filtering on compliant outbound toll-free SMS messages, check to make sure that you're not sending messages to Canadian mobile devices. Unlike in the US, mobile carriers in Canada treat SMS messages from toll-free numbers the same as any other SMS messages. This means toll-free messages are subject to the same filtering as standard long code SMS.
You can validate your messages are going to US phone numbers via the following methods:
- Check the
ToCountryparameter Twilio returns in API responses, and sends to your application for incoming messages.
- Look up the affected recipient phone number's area code manually, or via Twilio's Lookup API.
If you are following all best practices listed above, but your Toll-Free SMS to the US are still being filtering, please contact our Support team, and we can appeal to the carrier.
Why would I use toll-free instead of a short code?
A short code is the ideal solution for high-volume A2P use cases, and is the only acceptable option for sending marketing or promotional-type SMS messages in the US or Canada. By default, short codes offer much higher messaging throughput than other types of numbers, at 100 SMS segments per second. Short codes can also be enabled to send MMS (picture or media) messages in the US and Canada.
US-based toll-free phone numbers may be a better fit for certain use cases. Unlike short codes, they can be used for placing and receiving voice calls, in addition to SMS messages. Toll-free SMS may also be a good choice for a business that needs A2P-type communications, but are not ready to apply for a short code.
For a comparison of short code, Toll-Free US, and US/Canadian long code numbers, see Comparison of SMS messaging in the US and Canada for long codes, short codes, and toll-free phone numbers.