Why it matters
An invalid destination number error prevents your SMS from reaching the intended contact. Knowing the common causes helps you determine whether the issue is temporary, device-related, or requires follow-up with the recipient.
Key Concepts
Invalid destination number: A classification used by carriers when the recipient’s number cannot accept messages.
Recipient-side issue: A problem on the contact’s device, account, or service that prevents message delivery.
Carrier rejection: When the recipient’s carrier blocks delivery before the message reaches the device.
Why a Number May Be Deemed Invalid
The recipient’s carrier may reject your message for any of the following reasons:
Phone is turned off: The carrier cannot complete delivery while the device is offline.
Past-due bill: Messaging may be blocked if the recipient’s mobile account is suspended.
Number no longer in service: The phone number may have been disconnected or reassigned.
Recipient has blocked your number: All incoming messages from your number are rejected automatically.
Step-by-Step: Resolve an Invalid Number Error
Confirm that the recipient’s phone number is correct and properly formatted.
Ask the contact to ensure their phone is turned on and connected to a mobile network.
Confirm with the contact that their mobile service is active and billing is up to date.
If appropriate, ask whether they may have accidentally blocked your number.
If the issue persists across multiple recipients, contact Whippy Support to review potential routing issues.
Tips and Best Practices
Revalidate phone numbers before sending high-volume or automated campaigns.
Check recent communication history; sudden failures may indicate a block or number deactivation.
If uncertain, try contacting the recipient via call to confirm the number is active.
Troubleshooting
Issue | Possible Cause | Fix |
Message rejected immediately | Number disconnected or inactive | Verify number with the recipient |
Multiple failures for same contact | Contact’s phone off or service suspended | Ask contact to check device power and billing |
Sudden failure after prior success | Recipient blocked your number | Request the contact to unblock if appropriate |
Several contacts affected | Routing or regional carrier issue | Contact Whippy Support |