SMS messages can only be sent from a phone number or supported sender that is active, available in your account, and capable of sending SMS. If the selected sender is unavailable, incorrectly formatted, still being transferred, or does not support SMS, the message may fail.

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What Causes SMS Sending Number Errors?

Sending-number errors occur when the selected From number or sender cannot be used for the requested message.

A valid sender must be properly configured for the account and support the type of messaging being attempted.

Depending on the sender type, additional country or routing requirements may also apply.


Key Benefits of Verifying Your Sending Number

Checking the sender before messaging can prevent unnecessary delivery failures.

  • Fewer Failed Messages: Confirm the sender supports SMS before using it.

  • Better Number Management: Identify whether a number is active and available in the correct account.

  • Correct International Routing: Ensure phone numbers use the proper international format.

  • More Reliable Automations: Prevent workflows and campaigns from using unavailable or unsupported senders.


Common Causes

A message may fail when:

  • The sending phone number does not support SMS.

  • The sending number is not available in the current account.

  • The number is formatted incorrectly.

  • The number is still being ported or transferred and is not fully active.

  • A short code is being used for a recipient in a different country.

  • The sender has not been fully configured or provisioned.

  • A workflow or campaign is using an outdated or incorrect sending number.


Check Whether the Number Supports SMS

Before sending, confirm that the selected phone number includes SMS as an available capability.

  1. Go to Settings → Phone System → Phone Numbers.

  2. Locate the sending number.

  3. Review its available capabilities.

  4. Confirm SMS is supported.

  5. If SMS is unavailable, select another SMS-capable number.

A number may support voice without supporting SMS, so do not assume that an active calling number can also send text messages.


Check the Phone Number Format

Phone numbers should use E.164 format.

The expected format is:

+[country code][subscriber number]

For example:

+14155552671

Review the number for:

  • Missing country code

  • Incorrect country code

  • Extra spaces

  • Parentheses

  • Local dialing prefixes

  • Missing digits

  • Typographical errors

Correct formatting helps ensure the system identifies and routes the number properly.


Check Whether the Number Belongs to the Correct Account

The sending number must be available in the account being used to send the message.

Verify that:

  • The number appears under Phone System → Phone Numbers.

  • The correct account is open.

  • The number has not been removed or transferred elsewhere.

  • The workflow or campaign is configured to use the intended sender.

If the number is not available in the current account, it cannot be used for outbound SMS.

Check Porting or Transfer Status


A number being ported or transferred may not be ready for messaging until the process is complete.

If the number was recently moved:

  1. Review its transfer or porting status.

  2. Confirm the process shows as completed.

  3. Verify that the number appears as active in the phone number list.

  4. Confirm SMS capability is available.

  5. Retry messaging only after activation is complete.

Do not assume the number is ready for messaging simply because a transfer request has been submitted.


Check Short Code Country Requirements

Short codes are typically country-specific.

If using a short code:

  • Confirm the short code is approved for the recipient’s country.

  • Confirm the sender and recipient are in a supported country combination.

  • Use another eligible sender if the short code cannot reach that destination.

A short code approved for one country may not be valid for recipients in another.


Check Workflows and Campaigns

If the error occurs during automated messaging, review the sender configured in the automation.

Check:

  • Workflow sender settings

  • Campaign sender settings

  • Default sending number

  • Assigned phone number

  • Recently ported or replaced numbers

  • Sender selection after account changes

An automation may continue referencing a sender that is no longer active or SMS-capable.


Frequently Asked Questions

Q: Why can I make calls from a number but not send SMS?
Phone numbers can support different capabilities. A number may support voice without supporting SMS.

Q: What format should my phone number use?
Use E.164 format with a plus sign, country code, and complete subscriber number.

Q: Can I send SMS from a number that is still being ported?
Wait until the port or transfer is fully completed and the number is active for messaging.

Q: Can I use a phone number from another account?
No. The sending number must be available in the account being used to send the message.

Q: Can short codes send internationally?
Short code availability is country-specific. Confirm the sender is supported for the recipient’s country.

Q: Can workflows fail because of the sending number?
Yes. Automated messages can fail if the configured sender is unavailable, inactive, or not SMS-capable.


Need Help?

If SMS still cannot be sent, first review the sending number, capabilities, and account assignment.

Verify that:

  • The sending number appears in Phone System → Phone Numbers.

  • The number supports SMS.

  • The number is active.

  • The number is formatted correctly.

  • The number belongs to the current account.

  • Any porting or transfer process has been completed.

  • A short code is being used only for supported destinations.

  • Workflows and campaigns are using the correct sender.

  • A recently replaced or transferred number is not still selected in an automation.

If the issue continues, collect the sending number, destination number, sender type, SMS capability status, porting or transfer status if applicable, workflow or campaign name, and screenshots of the failed message before contacting support.