Following are some of the common reasons why the messages don’t get delivered:

1. Sending messages to invaid number like Landline
2. Mobile switched off or out of network
3. Destination number has opted out
4. The Message subscription on the destination number has expired (e.g.- Customer having 1:1 communication and suddenly a message is not delivered).
5. Spam Detected- Too many messages sent using long code, like bulk or campaign (We suggest either Shortcode or Toll free number).
6. Number has opted out from receiving messages from you.
7. Number is overwritten
8. The end-user’s mobile plan does not support SMS
9. Number is no longer valid
10. Prepaid subscription for SMS expired
11. The sender id entered is either not in the correct format, not SMS-enabled or not assigned to your account.
12. Network error- Network issues at carrier end
13. Spam detected- SMS filtered
14. Invalid SMS Content- blank SMS or SMS exceeds the characters limit of 1600 for messages