All Delivery Receipts with a non-zero error code can be considered as indicating failed delivery. i.e. Your SMS did not reach the recipient.
Neither Nexmo SMS APIs nor operators will perform further attempts to re-deliver a message unless another API call is performed.
Nexmo error codes:
Error | Meaning |
---|---|
0 | Delivered |
1 | Unknown |
2 | Absent Subscriber - Temporary |
3 | Absent Subscriber - Permanent |
4 | Call barred by user |
5 | Portability Error |
6 | Anti-Spam Rejection |
7 | Handset Busy |
8 | Network Error |
9 | Illegal Number |
10 | Invalid Message |
11 | Unroutable |
12 | Destination Un-Reachable |
13 | Subscriber Age Restriction |
14 | Number Blocked By Carrier |
15 | Pre-Paid Insufficient Funds |
95 | Unknown |
99 | General Error |
For further information see: Why was my SMS not delivered?