The issue might be to do with:
2. The network congestion of your operator, which may cause delays in receiving SMS.
3. The recipient's mobile phone memory, which may be full.
4. Time. If the recipient has been out of the service area for a long time, the SMS may have timed out and been deleted by the SMS centre.
5. Sensitive words, which may have been deleted by the operator in the SMS Centre.
Confirm the SMS number is correct and contact our Customer Support for further assistance if the issue persists.