SMS Delivery: Statuses, Troubleshooting, and Regional Guidelines
All SMS notifications sent through your OnceHub account are recorded in your SMS logs. Use this article to help you understand delivery statuses, resolve common delivery failures, identify sender information and ensure compliance with regional carrier requirements.
Understanding SMS Delivery Status Definitions
Your SMS logs display one of the following statuses for every message sent:
- Delivered: The message has reached the recipient’s device.
- Sent: The message was sent but a delivery receipt is pending. This is usually a temporary status while the message is in transit.
- Rejected: The message was not sent because the phone number was identified as invalid.
-
Failed: The message was sent but could not be delivered to the recipient.
Section titled “Failed: The message was sent but could not be delivered to the recipient.”
Troubleshooting Delivery Failures
Section titled “Troubleshooting Delivery Failures”When an SMS fails, OnceHub provides a specific error message to help you identify the cause.
| Error Message | Meaning | Recommended Resolution |
|---|---|---|
| Illegal Number | Invalid phone format. | Verify the recipient’s number and country code. |
| Absent Subscriber | The number is disconnected/ inactive. | Confirm the mobile number with your customer. |
| Call Barred by User | Recipient blocked incoming SMS. | Recipients must contact their carrier to unblock. |
| Portability Error | The number recently moved between carriers. | Database sync issue; usually resolves within 24–48 hours. |
| Anti-Spam Rejection/ Invalid Message | Carrier rejected the message because of the message content / sender ID | 1. Ensure the message doesn’t contain high-risk keywords (e.g., “loan”, “debt”). 2. See How to Manage Regional Limitations (Singapore & Turkey) section below for specific rules. |
| Handset Busy | Device unable to receive (e.g., full inbox). | The system will automatically retry. If the error persists, manually try sending the message again later. |
| Network Error | Carrier network congestion or outage. | This is usually a temporary carrier issue. Wait a few minutes and manually resend the message. |
| Unroutable | Carrier cannot route to this number. | Check for regional limitations or verify the number. |
| Destination Unreachable | General routing failure. | Verify the recipient’s number is correct. If it is, attempt to resend the message after a short delay. |
| Number Blocked by Carrier | Carrier-level block on the device. | Recipients must contact their carrier to enable SMS. |
| Subscriber Opt-Out | The user has unsubscribed. | See How Guests can Opt-Outs of SMS Notifications (US & Canada) section below. |
| Prepaid - Insufficient funds | Prepaid plans cannot accept SMS. | The receiver must top up their balance or check their mobile plan. |
| General Error | Unknown carrier or internal error. | Wait for 15–30 minutes, then manually resend the notification from the SMS logs. If the error persists, Contact OnceHub Support for technical investigation. |
How to Identify OnceHub Sender Information
Section titled “How to Identify OnceHub Sender Information”OnceHub uses consistent Sender IDs to ensure high deliverability. You can share these Sender IDs with your customers so they can whitelist them or save them as a contact to prevent messages from being flagged as spam.
- United States: 1-844-200-5585
- Canada: 1-204-272-8408
- India: Random Numeric Sender ID (e.g., 59039465)
- Rest of World: Appear with the Sender ID OnceHub
How to Manage Regional Limitations (Singapore & Turkey)
Section titled “How to Manage Regional Limitations (Singapore & Turkey)”Carrier policies in certain regions may impact delivery even when a Sent status is displayed.
Singapore
Section titled “Singapore”SMS deliverability is highly restricted by local authorities. Automated messages are frequently blocked at the carrier level. Recommendation: Because OnceHub does not differentiate notifications by region, you cannot enable email alerts for specific countries. If you have customers based in Singapore, we recommend enabling Email Notifications in your Booking Calendars to ensure they receive meeting details.
Turkey
Section titled “Turkey”Turkish carriers strictly filter messages containing URLs, often leading to immediate delivery failure. Requirement: Because OnceHub does not differentiate notifications by region, you cannot apply specific SMS templates to different countries. If you have customers based in Turkey, you must ensure your SMS templates are plain-text only and do not include links (e.g., Cancel or Reschedule links) to avoid carrier blocks.
How Guests can Opt-Out of SMS Notifications (US & Canada)
Section titled “How Guests can Opt-Out of SMS Notifications (US & Canada)”In compliance with carrier regulations, recipients in the US and Canada can unsubscribe from all OnceHub notifications at any time using some standard Keywords. To opt-out, recipients can reply to any SMS with: STOP, END, QUIT, CANCEL, UNSUBSCRIBE, REVOKE, or OPT OUT. These keywords are not case-sensitive.