When sending outbound SMS, I received delivery receipt error code 4.
- Outbound SMS
- Delivery Receipts (DLRs)
- Error Code 4
Delivery receipt error code 4 Call Barred by User is a permanent error. The number should be removed from the client's database.
If the end user wants to receive SMS, they should contact the network operator directly to resolve this issue.
For more information see, What happens when you send SMS to a barred number?