If you encounter the following error message, there are several possible reasons for this.
Error 4750
If the issue only happens to one particular number, it could be due to a number of reasons - the recipient's number could be a prepaid user whose account is out of money, a subscriber that is provisioned to not receive this type of SMS or it was identified as Spam. Alternatively, it is also possible that your contact has blocked you or there are some other restrictions that we cannot check at this point of time.