Invalid numbers and rejected messages
A message can be rejected even before sending (validation on the platform side) or after attempted delivery (rejection on the operator side).
Rejection before sending (platform validation)
- Incorrect number format (missing area code, invalid digits)
- Number appearing on your internal blacklist (previous STOP unsubscription)
- Insufficient balance
Rejection after attempt (operator side)
- Number non-existent or canceled
- Line suspended for unpaid
- Incompatible line type (some landline or VoIP numbers cannot receive SMS)
Clean your contact database
Use our HLR verification feature (see API documentation) to validate the active status of a number in advance before including it in a campaign, reducing the rejection rate and optimizing your budget.